i watch horror movies while tripping but its usually a really old movie. one of my favorites is Dracula from 31. its slow and atmospheric rather than full of jump scares. no gore or anything and the most sfx you'll get is a rubber bat on a string. no not scary by modern standards but still a fun watch if you are into horror or the history of film making. plus the benefit of it being in black & white is the large open sets give your brain plenty of room to play around with visuals.

i've also watched some modern horror but usually still a slower movie like Lamb or The Lighthouse. Color Out of Space is good and very trippy but gets pretty intense toward the end.