One idea could be that the United States is transported to a world of magic. The government tries to adapt by creating a new department to study and regulate magic. For example, the military might start developing magic - based weapons.
Maybe the United States in this other world is much smaller in size, and has to form alliances with strange new species to survive. They could trade their technology for resources that are unique to this new world.
Another plot could be that in this other world, the United States discovers that it is a part of an ancient prophecy. The country then has to figure out its role in fulfilling or preventing the prophecy, which involves dealing with powerful and otherworldly forces.
A military general could be a main character. He might be the one leading the charge in exploring this new world and dealing with any threats that come their way.
One idea could be that Zoro ends up in a world full of magic. He has to learn to adapt his sword skills to combat magical creatures. Maybe he teams up with a local wizard who helps him understand the new world's rules while he teaches the wizard about honor in battle.
Perhaps Goku lands in a world where the inhabitants are all pacifists. He has to find a way to protect this world from an external threat without using his usual brute force, which could lead to him developing new skills. Also, he might find himself in a world with a different concept of time, which messes with his ability to power up in his usual way.
One idea could be that the Akatsuki members are transported to a world full of magic. They have to adapt their ninja skills to this new environment. For example, Sasori might find new materials to create his puppets, and Deidara could be intrigued by the different ways to create explosions in this magical world.
One idea could be Naruto arriving in a world full of magic, and he has to learn to combine his chakra skills with magic. For example, he might use his Rasengan with a magical spell to create a super - powerful attack.
Another plot could be that Vegeta lands in a world where time moves differently. He might age at a much faster or slower rate. This would add an extra layer of complexity as he tries to figure out how to get back to his own world while dealing with the changes in his physical state and the relationships he forms in this new world.
Maybe in this other world, Ichigo discovers a group of people who are similar to the Soul Reapers but have different powers and a unique hierarchy. He could get involved in their internal conflicts and help bring peace while also trying to find a way back to his own world.
One idea could be that America is in a world where magic exists. The government has to adapt to regulate magical powers. Another could be a world where America is the only non - technological nation and has to rely on old - fashioned ways while other countries thrive with advanced tech. And perhaps a world where America is split into multiple kingdoms and there's a power struggle between them.
One idea could be a mystery that the whole village has to solve together. For example, strange things start happening like crops failing in a pattern that seems unnatural. The villagers, who are usually divided by small feuds, must put aside their differences and work as one to figure out what's causing it. It could be a magic spell gone wrong or some sort of creature causing trouble.
One idea could be the OC has unique powers from their world that are completely foreign in the new world they end up in. For example, they might be able to control time in a very different way than the native magic users. Another could be that the OC's appearance is so strange that they are initially feared or worshipped. They could also bring a new form of technology or knowledge that disrupts the existing social order.