I don't trust the Windows 10 HDR implementation and most PC monitors can't do HDR properly. I just recently was looking for a new monitor, that has both great color gamut range, high refresh rate and resolution, low latency and won't burn in quickly; and there's none. The best of the best can cover about 80% maybe out of 100% gamut, while still having the rest of latency/refresh specs. The tech isn't there yet. Unless you go for color gamut alone, and forget the latency parts. Can't be both. Yet.
I won't say that isn't nice to have this option in BG3 or doesn't look great; it's better than nothing and not everyone is looking for perfection: will be less details in dark scenes, but will work somehow.
Here is a quote from a very good review of the current best HDR gaming monitors:
"Although HDR is extremely common on TVs, it's just starting to gain popularity on monitors. Unfortunately, most monitors are a few years behind TVs when it comes to HDR performance. Despite this, there are a few monitors that deliver a decent HDR gaming experience. As more and more games support HDR, we expect the demand for good HDR monitors to increase drastically over the next few years." https://www.rtings.com/monitor/reviews/best/by-usage/hdr-gaming
I just manually adjust everything using this Reshade variant: GShade "GShade is a highly modified ReShade fork & package with a selectively network-unlocked depth buffer and numerous improvements"https://github.com/Mortalitas/GShade
Reshade is fine as well, but some games like Black Desert Online and others have anti-hack protections that won't allow Reshade, because the network part. So I have all my custom settings in GShade, and works fine with BG3 in Dx11 mode. I don't have much on, just a bit of sharpen and such, the colors are already very well done (on highest settings at least).
So in case you don't have HDR or don't like the results, GShade or Reshade is an option as well to fine tweak graphics details further.
Edit: forgot to add that the main reason I'm using this in BG3 is to make screenshots through this, since BG3 has no screenshot function (yet), also to display FPS and maybe the clock, though a bit of sharpen filter helps as well.