If everything looks better with HDR off, it's likely that the HDR on your display is crap, some "HDR" displays can only take a HDR signal and can't even output HDR. If you're not using an OLED or mini-LED display, just forget about HDR.

Anyway, as for game support, it varies, some games require you to have HDR enabled in display settings before it'll work, where as other games will allow you to enabled HDR without it being enabled in display settings.

When i got my new pc, my hdr was crap. It make NO MANS SKY look super goopy and dark. Turning it off actually improved the graphics in the game. I have never seen a HDR that makes games look better...maybe on newer hardware maybe?

would u say that this is a hdr picture
https://imgur.com/a/wTOBWXN
isnt too gray???is that normal???

can someone tell??

Choose whatever setting you think looks better. If you don't like how your desktop looks with HDR enabled, but you want to play an HDR game that requires Windows HDR to be on, you can use windows-alt-b to toggle HDR on/off. I have dual monitors, and, on my PC, that overrides my previous settings and sets both monitors to a single setting. I dislike that because I want one monitor set to "HDR on" and other monitor set to "HDR off".

I find my HDR photographs look better on the more expensive monitor that has HDR1000 support. That's the monitor where I leave HDR enabled, though some things look a bit too washed out or bright. I'm sure I could adjust that and make it look better, but I'm too lazy right now.