I'm downloading GT sport cause of exactly that, everyone says it's the best hdr but god almighty it's nearly 90 gigs now. And yeah, I turned tetris effect HDR on manually in game, it's good yeah, it just the FoV blocks most of the effects outside of vr.
I think the best thing I've watched in 4k hdr was some videos of fireworks in youtube, it's definitely a video medium and has yet to be taken advantage of in games fully.
Oh, wait until you play GTS. The sunset versions of the tracks look very real as well as night time. TVs aren't quite bright enough to make sunny day time contrast look like outside yet the morning and late afternoon almost have it spot on and lighting at night is sublime. There is fireworks too in GTS! Not sure where yet completing a Tokyo race at night in FIA championship had lovely fireworks in the last lap.
It added a lot in SotC as well in the darker scenes. So much any screenshots were doomed. Day time looks a bit nicer due to the brighter sky. SotC has a static sky box though, very lovely in HDR yet doesn't change much.
You can change the FOV in Tetris Effect on TV, zoom in or out and look around. It's easier in VR of course yet some effects look pretty flat in VR. It's a toss up, completing journey mode looks amazing in both.