Like there is a hidden world of wizards, but independent there is also a hidden world of martial arts like wuxia, then a hidden world of like spiritualism, then a hidden world of aliens, etc all of them exist as like a hidden side of the world but non of them really know about the others until some event causes them to intersect or the protagonist stumbles into them
by Hankitty19
1 Comment
Dreams and Shadows by C Robert Cargill sort of fits this. Fairy world, real world, heaven and hell are all different worlds that interact in an urban fantasy setting.