To watch a game in Dolby Vision, you will need a streaming system (TV, device) that supports Dolby Vision. A 4K TV that does not support Dolby Vision will not be able to receive the DV signal.
Microsoft has just launched support for Dolby Vision HDR gaming on Xbox Series X and Xbox Series S, with support in over 100 games. And "thousands" of other games that are available in HDR will be ...
The Xbox Series X does support Dolby Vision for video games and streaming, but it doesn't support this HDR format on discs.