The Evil Within does not work properly fullscreen @ 4K. You need to mess around with it otherwise you only get 25% of the screen vs 4K with black bars either side
Fallout 4 - does not work properly either in full screen mode
Minimal if zero QA on these 2 titles
Probably werent too many people playing in 4k 7 years ago when Evil Within came out, or is it a remastered edition or something on gamepass?
EDIT : Heres the solution to 4k in Evil Within https://steamcommunity.com/app/268050/discussions/0/135507548119956979/