Alternate Realm Boon

Isekai fiction has the common trait of having the protagonist receiving a power, skill, or even a legendary item that gives them an overwhelming advantage over the inhabitant of the other world.

Common in most Eastern Portal Fantasy light novels where it is a power(s) that can make a massive benefit or the go-to means for the protagonist to use, especially in combat. The settings of the other world take place in a world that has RPG features that come in the form of a skill. Others would have magic within the setting where the main character has a high affinity and even using the modern study of science in combination for higher effectiveness. For the case of items, they are usually legendary weapons that are known in the world to be wielded by the summoned hero in order to face a danger the inhabitants cannot without a chosen one brandishing it. Another fascinating example is characters who are reincarnated by a deity and are blessed with something that eases any difficulty in a new world. Another method is reincarnating into a high-class monster or a non-human being.

Western Portal Fantasy seems to use the trope within such stories rarely. They often would be placed in a fantasy setting where their modern education or even technology would give them an advantage.

Anime and Manga

 * In Arifureta: From Commonplace to World's Strongest, the students and their teacher got a job and magic when they transported to another world besides Hajime, who is the main protagonist. He gets stuck with the rare job of Synergist that is a non-combat one with the power of transmutation that can act as a craftsman or blacksmith.
 * Rising of the Shield Hero has four people from a different world summoned with Four Legendary Weapons. The four Legendary Weapon comes in the form of a sword, spear, bow, and shield. The weapons grant their users different abilities while also having different forms under certain conditions or absorbing materials. The protagonist’s Legendary Shield gives him a high amount of defense but lacks offensive capabilities like the others.
 * Re:Monster has the main character Tomokui Kanata who was reincarnated into a goblin named Rou. He kept his memories and his Esper ability called Absorption. The ability allows him to eat anything from a living creature to material no matter how hard or toxic. The strength of the ability gained depends on the condition.
 * Wise Man's Grandson has the main character, Shin Wolford, who gets reincarnated with vague memories of his previous life. He learned to control his magic power and chantless magic from the Wise Man Merlin and Guru Melinda. Shin combines magic with the knowledge of modern science for powerful effects and new forms of magic. There is also how he uses Enhancement magic to modify clothes and accessories better than Guru Melinda. The application is made by using Kanji instead of the alphabet used in the world, which can give more options for customization.
 * Knight’s and Magic have the main character, Ernesti Kurata, who was a genius programmer and mecha otaku reincarnated into a world where magic and mecha called Silhouette Knight exist. He realizes that magic is like computer programming. Ernersti applies this to use high-level magic at an early age by reprogramming his own internal Magic Circuit with subroutines. He also uses this same knowledge to reprogram and improve the Magius Engine of a Silhouette Knight. There are also the inventions he has developed, such as a wand that can be used for close combat and innovations to the magical mecha.
 * Parodied in KonoSuba: God’s Blessing on this Wonderful World!, where a shut-in NEET, Kazuma Sato, dies from shock after mistaking a tractor for a truck while trying to save a girl. He is offered the opportunity to reincarnate into a world that’s like an RPG under siege by the Demon Lord. Along with reincarnating, he then is offered his advantage to use in the new world by a goddess named Aqua. Kazuma then chooses Aqua as his bonus, and another goddess recognizes it as official, then they both get teleported to this world.
 * Konjiki no Word Master has five teenagers summoned, but only four of them are the heroes are there to save the kingdom. Each hero has their own advantages like affinities for all elements of magic or talented with physical actions. The fifth is the main character with the title, Innocent Bystander, but can use the unique Word Magic. The magic has him draw Kanji and apply the meaning of it as an effect.
 * World Strongest Rearguard: Labyrinth Country and Dungeon Seekers have a man named Arihito Atobe reborn as a Seeker in the world called Labyrinth Country. After getting his Seekers License and chooses the Rearguard job which is different compared to the other jobs like Valkyrie and Priestess.
 * Death March to the Parallel World Rhapsody has Suzuki Ichiro, who was a 30 programmer that died from exhaustion and ended up reincarnated into a younger body. He then sees that he pull up screens like in a game, and then uses the three use skill of Meteor Shower against an army and levels up to 310.
 * Downplayed in So, I'm a Spider, So what?, where people who reincarnate into the world with the skill, n%I=W.
 * Deconstructed in Re: Zero, where the protagonist Subaru Natsuki has the ability he calls Return from Death when he is transported to a fantasy world. He can return to a previous time or a ‘save point’ after death. Other than that, he is an average human with no other supernatural abilities.
 * That Time I was Reincarnated as a Slime has Satoru Minami gets reincarnated after getting killed by defending his subordinate from getting stabbed. Due to how he died a virgin, he gained the Unique Skill of Great Sage along with other skills such as immunity from pain, resistance from electricity and heat such as fire and ice.
 * In Another World with My Smartphone, where the main character, Touya Mochizuki, is accidentally killed by God and reincarnated into another world. He is granted a body with superhuman abilities and uses all seven magical elements. There is also his smartphone that can be charged with magic power and can access the internet from Earth.
 * Overlord has the protagonist, Suzuki Satoru, being transported to the New World as his Yggdrasil character, Momonga, along with the guild headquarters and all the NPC subordinates. The New World acts much like the game, along with how his character has been leveled up to 100.
 * Isekai Cheat Magician has the two protagonists, Taichi and Rin, who are summoned to the new world and gain new powers. Taichi is gifted with a massive amount of magic power, which can be used to gain superhuman physical abilities. Rin gains her own reservoir of magic power while also showing affinities for earth, wind, fire, and water magic.
 * Reincarnated as a Sword has a 30-year old salary man show was killed in a driver who was texting while driving and reincarnates into a living sword. He can gain new skills by slicing the magic crystals of monsters. These skills can be used by anyone who wields him along with the stats he carries. One unique feature from other weapons is his Mana Conductivity ranked at A which means that his weapon sharpness and power can be increased by 200% when coated with mana.

Literature

 * In John Carter of Mars, the titular character travels to Mars by having his soul teleport through space and gains a new body. Due to the lower gravity, he gains superhuman agility and strength.
 * Everworld where the teens can bring modern technology and knowledge to Everworld where they give them advantages such as trading a recipe for gunpowder or using conventional weaponry.

Video Games

 * Fantasy Boyfriends: Legends of Midearth game has a young man being summoned as the legendary hero that is the only one that can wield the sword that can defeat the Demon Lord.
 * Tokyo Afternoon Summoners takes place in an alternate Tokyo where people from 23 different worlds are summoned due to an app and are called Transients. Each Transient has a Role and is summoned with a Sacred Artifact that gives a Rule to their Transient. A Rule is a power that correlates to the Role of a Transient. An example would be a person given the Role of Fighter, and their Rule is Infinity.

Web Comics

 * I am the Sorcerer King webtoon has people called Awakened who gain a superpower and become connected to the Akasha System along with fighting monsters that come from portals. Lee Sunghoon awakens to his past memories and magic of being the reincarnation of The Great Sorcerer, Kurataurus, who is from another world. The incident happens after being attacked by a monster and becomes one of the Awakened which connects him to the system.

Western Animation

 * In the opening credits of the 1980s Dungeons and Dragons cartoon series we see Dungeon Master gifting the trapped teenagers with the magic items that grant them powers (and character classes) they need to survive.