Realm Exclusive Effect

 wtsKZIzYIf0 An average person finds himself in another world where they may come across learning they have superpowers or an item that can grant them one. After being sent back to the real world, the person would have no powers. The nature of the other world would have an empowering effect on people or certain items. This trope involves two worlds that can be accessed through different means like teleportation or a portal.

Heavyworlder is a subtrope more common in Sci-Fi. See also HAD to Be Sharp for adaptations or training forced by harsh environment (natural or unnatural) on its inhabitants.

A staple trope of the Portal Fantasy sub-genre.

Anime and Manga

 * Yumeria has anyone that enters the dreamworld called Moera to gain different outfits, powers, and weapons. An example of this is the main character can also give the others a boost in power while also showing superhuman strength.
 * Averted in Fairy Tail, where the characters are brought to Edolas and can't use magic unless they use specific equipment. This problem is solved when they swallow a crystal, which allows them to use magic normally.
 * In Dream Eater Merry, Yumeji has an ability he calls Lucid Gear that can only be used in a Daydream.
 * There is also Ren Hinaki, who shared a symbiotic relationship with the Dream Demon, Quartier Latin. When in a Day Dream, they can do a Dream Phase Union that can allow him immunity from dream loss when a Dream Demon is killed. It also gives him a weapon called Tazer Arm, which acts like a giant taser and used for his signature attack, Dream Corridor, that can bring a Dream Demon back to the Dream World. He can also use his Dream Demon's Day Dream to hinder an opponent during battle.
 * Played with in the manga Isekai Ojisan: when the titular character was dragged to a fantasy world, he didn't have any special powers there, but he was able to learn the local magic. Then he is returned to the modern world 17 years later, he still has the knowledge and can use magic.
 * El-Hazard: The Magnificent World, one of the earlier Isekai licensed for release in North America, has four people gain powers when they are transported from Earth to El-Hazard. (Which powers they get depends on which continuity they are in.) At the end, at least one of the people returns to Earth.
 * There's no evidence that the main characters of Magic Knight Rayearth get to keep their new-found abilities when they return to Earth.
 * MÄR has people from Earth that are teleported to MÄR-Heaven gain superhuman strength and better eyesight due to it's lower gravity.
 * In The Devil is a Part-timer, magic on Earth is limited and that other means are needed to use it. The magical world of Ente Isla has magic in abundance that can be used without any restriction. An example would be demons who need the negative emotions of humans to use their form of magic while also regaining their demonic forms.
 * In Log Horizon, gamers get spells and powers based on their in-game avatars. When in the real world, they're just typical normal humans.
 * Flip Flappers has the world of Pure Illusion where those who can synchronize with a crystal called an Amorphous Piece to gain the power to Flip Flap. This process gives the Flip Flappers magical powers with a transformed state that provides access to superhuman abilities along with weapons.
 * Yuki Yuna is a Hero has the members of the use the Hero System go into another realm called the Jukai in order to defend the Shinju from the Vertex. When they are in this other reality, they gain superhuman strength, speed, stamina, eyesight, armor, and a Fairy. Theses Fairies support their heroes by giving them weapons and other powers to fight the Vertex.
 * Haruhi Suzumiya have Espers that cannot access their powers unless in a Closed Space or a similar dimension. The only powers they have in the real world are sensing the Closed Spaces and entering them.
 * Corrector Yui have people called Correctors who use a ComCon to go into the ComNet without a VR unit. As a Corrector in the ComNet, they can use Element Suits that are given by Corrector AIs.
 * An interesting example from Infinite Dendrogram
 * Fairy Tale Battle Royale have people appear in fairy tale settings as the main characters of those stories. Depending on the fairy tale character, they granted their abilities, much like the fictional character. An example would be if their character is Peter Pan, the person would be able to fly.
 * In Digimon Tamers, the Tamers and their Digimon partners can Biomerge in the Digital World to reach their Mega levels. In the real world, they cannot Biomerge like in the Digital World due to not being made of data. There are alternatives in the real world but only work in limited instances or within the quantum bubble of the D-Reaper.
 * Downplayed in Kinnikuman: By invoking Bergmann's Rule, Lunaight can tower over his opponent. This ability can best be used on the Planet Earth, as his ancestors originally came from there. He can't use this ability in the Omega Cluster at all because that won't awaken his ancestors' genetics. Still, he's a powerful Chojin, so he doesn't need to rely upon Bergmann's Rule.

Comic Books

 * The manfra Dreamland has "Travelers" who gain access to the titular setting by facing their phobias and gaining power related to them (one power each).
 * The original Amethyst, Princess of Gemworld series featured Amy Winston, a normal teenage girl who travels to the magic-ruled Gemworld and transforms into Princess Amethyst. While on Earth, she's a normal girl without any powers; on Gemworld, she possesses the magical powers of the House of Amethyst.

Literature

 * In The Chronicles of Narnia, the Pevensies are just normal British kids living in the 1940s on Earth, but in Narnia, they're powerful kings and queens with reputations similar to that of King Arthur's.
 * The titular John Carter of Mars gains superhuman strength and agility when he is on Mars (or "Barsoom"), due to its lower gravity.
 * The colonists of the world Pyrrus in Harry Harrison's 1960 SF novel Deathworld are Heavyworlders because Pyrrus has a gravity twice that of Earth, but that's not where it stops. The entire planet is actively hostile to the human colonists – every single life form on it, down to the plants, is trying to kill them. The colonists are trained from the moment they're in diapers to kill or be killed, just to survive. The few that leave Pyrrus are unstoppable juggernauts offworld.

Live-Action TV

 * In Denkou Choujin Gridman, Naoto with the use of the Acceptor and the computer made of junk parts called Junk to fuse with the Hyper Police, Gridman, to fight Kaiju in the Computer World. These giant monsters are created by Takeshi while brought to life and under the control of Khan Digifier, to cause chaos in the Computer World. Depending on the building in the Computer World, computers or electronic devices will be affected by some form of destruction or alteration that causes malfunctions in the pieces of technology. Gridman has special attacks for offense and defense against Kaiju. One of the most important of his attacks is the Grid Fixer Beam, which can fix any changes made by the Kaiju in the Computer World, thus causing any affected technology to function properly. Gridman also has access to Assists Weapons that are created by Ippei that can help him fight the Kaiju. These Assist Weapons can boost Gridman's abilities and can come in the form of weapons that he can wield or vehicles and mechs that can turn into a suit of armor.
 * MOD: I need help figuring out what this one is supposed to say. Does the Computer World cause chaos, or do Kaiju cause chaos in the Computer World, or do Kaiju cause chaos in the real world until they're fought in the Computer World? "He has access to help": Who is "he"? Does he use that access, or is it just sitting there doing nothing? "with Yuka and Ippa's assistance": who do they assist - Junk or "he"? Are the Assists Weapons the assistance, or is making the Assists Weapons the assistance? Overall, this example needs a complete re-write.

Tabletop Games

 * An inverted example from d20 Modern's "Urban Arcana" setting: monsters from Dungeons & Dragons fall to Earth as "Shadowkind". Monsters that are large physical combatants aren't special on their home world, but pose the greatest danger in the "real" world due to the high density of civilians, weapon restrictions, and the lower power level of heroes (especially heroic magic users). This is especially true of anything with damage reduction that requires magic to bypass it -- in D&D one is expected to have a magic weapon by about level 4 and can find ways to have one temporarily from the first level, but in Urban Arcana any kind of magic weapon is exceptionally rare and likely archaic even if you find one.

Video Games

 * In Tokyo Xanadu, certain people can use armaments called Soul Device while in a place called the Eclipse. The Eclipse is an overlap of the real world and the Spirit World where monsters called the Greed dwell.
 * Subverted in Persona 4 and 5 where the characters can summon their Personas while in the TV World and Metaverse, respectively. The characters within the setting believe that they can only call them in the alternate dimensions. They can still summon their Persona, but they would need to under heavy duress or the use of an evoker.
 * The Longest Journey has the two worlds of Stark and Arcadia that each society is based on science or magic, respectively. A shifter can go between the two and have access to magic while in Arcadia. Stark favors science and technology compared to the use of magic in the Arcadia.
 * In Viewtiful Joe, the V-Watch cannot be used in the Real World and only in Movieland. The V-Camera, introduced in Double Trouble, is used to circumvent this limitation, by filming Joe to transform into his alter ego.
 * The Mario Bros., in Mario & Luigi: Dream Team, are as strong as they normally are in the rest of the Mario & Luigi series. But in the Dream World, Mario gains a mild boost to his stats, and his regular attacks are turned into crowd-clearing AoE moves.
 * The Holy Instruments, from Dual Hearts, can only take form in the Dream World, which can be by used Rumble.
 * In Tokyo Mirage Sessions ♯FE, there is the Idolasphere where monsters called Mirages resides and feast on people's Performa. Performa is the creative energy people have, when drained by a Mirage, leaves a sense of despair. There are certain people called Mirage Masters who bond with a Mirage by giving their Performa willingly to the monster. These Mirage Master have an extraordinary Performa, and their Mirage grants them powers along with an appearance similar to the monster's form when in the Idolasphere.
 * In Mega Man Star Force series, a compatible human and EM Wave being can perform an EM Wave Change that allows access to the Wave World. The human can interact with devices, access to the powers of the EM Wave being, and can use Battle Cards as weapons.

Web Comics

 * In the Layers webtoon, certain teenagers can teleport to another world called Layer and have the powers such as telekinesis or copy objects while there. Once someone becomes an adult, they lose the ability to teleport to this other realm.
 * In Her Summon webtoon, Jin-Kyung is summoned from modern-day South Korea to another world by a Summoner. While summoned, he gains magical powers through the use of ordinary objects brought with him. He uses these mundane items as a conduit for spells, but the item gets used up. Examples would be how a battery would become dead or an insecticide getting emptied. When he is teleported back to Earth, he loses any magic, and any spell he tries doesn't work even if the proper item hasn't been used.
 * Hardcore Leveling Warrior has
 * In the Dreamland Chronicles, Alex when in Dreamland has the Sword of Kings when he goes into that world. He also has magic armor and the ability to fly.

Western Animation

 * In Midnight Patrol: Adventures in the Dream Zone, a group of children and their dog are normal until they fall asleep and enter the Dream Zone. The dog gains the ability to speak, and the children get some sort of power or a magical object. The one exception would be Rosie, while part of the Midnight Patrol, doesn't get any power or item.
 * In Twelve Forever, the three protagonists can teleport themselves to Endless Island, where each has a unique power and a new look. Twelve get superhuman strength, Esther can create whips of light along with a small planet she could ride, and Todd is a shapeshifter. Later on, other children can be transported to Endless Island and gain a superpower.
 * In Penn Zero: Part-Time Hero, Penn, Boone, and Sashi take over heroes in another dimension that may have superpowers or other abilities depending on the overshadowed hero. The villains, Rippen and Larry, may get powers much like the heroes depending on the villain they possess.
 * In Code Lyoko whenever a person gets Virtualized into Lyoko to gain a form and abilities that seem to be based on their personality.
 * Magic chalk, from Chalk Zone, is ordinary chalk while in the real world. It can open a portal to the titular zone and draw anything when in an artist's hands. The chalk can only draw in the hands of a human artist and can't be used by the inhabitants of Chalk Zone.
 * Space Jam has any person who enters the Loony Tunes World gain the same attributes of a cartoon character such a being inflated like a balloon to stretching their arm.
 * He-Man and the Masters of the Universe: Averted, in Orko's home dimension, he's a very good mage and enough to challenge the Istari. Whereas Eternia's magic environment crippled him so much that he comes across an inept. Even though he is weakened, he has been learning how to use magic from scratch in Eternia, which gained Adam's respect.