Xbox
It’s taken a couple of years for the Xbox app to catch up with PlayStation 4 that supported HDR back in 2019, but it’s not like there is a ton of great content with HDR on YouTube that you’ve been missing out on.
To test your Xbox settings, YouTube app, and HDR TV seach for 4k HDR content on YouTube and within the app click on the “stats for nerds” display. You should see bt2020 following the “Color” output specification.
Unfortunately, the maximum resolution for Xbox One is 1080p, but there is some good content on YouTube for the newer models that support 4k/HDR.
From Microsoft
“You can now watch YouTube videos on the Xbox Series X|S. In the YouTube app you can view your subscribed channels, search for content, and use your mobile device as a remote.”
“YouTube is available in 4K on Xbox One S, Xbox One X, Xbox Series S, and Xbox Series X models. The maximum resolution for the original Xbox One console is 1080p. HDR playback is supported on Xbox One S, Xbox One X, Xbox Series S, and Xbox Series X models.”
Source: YouTube Help via FlatPanelsHD