Gate: Jieitai Kanochi nite, Kaku Tatakaeri, Re:Creators Recommendations
Both have main characters crossing worlds and being confused about it.
Re:Creators has a really original premise: fantasy chars appear in modern Tokyo, not knowing they were watched by Otaku as anime/game characters, and now have an opportunity to find their writers and animators and beat them to a pulp if they want; one young otaku gets an accidental prime spot as an improvised "Japanese host" for the girls (after some sketchy events ofc), then a plot appears and there are fights between those characters everywhere!
Gate has the Japanese SDF cross a gate to a fantasy world, face its armies and after
In both stories the anime/other world bacomes reality. The people from the anime/other world as well are the people form the real word fight for their beliefs. Both male MCs like very much anime/manga/light novels and also like to come in contact with the people for the anime/other world.
Both have the same plot where powerful beings from another dimension comes to another world where they have established themselves as the superior ones, however , in Gate it involves humans coming in from a portal that connects to their world to the world of fantasy , in Re:Creators in the other hand it was a complete reversal, where it involves, the works of man coming to life and running amok into the real world.
Isekai genre. The characters have mixed timelines and went to Earth. Great action scenes. Entertaining to watch.