Help me out here, maybe I misunderstand.
I've done a ton of research and RGB FULL means that you are setting the video range to be 0-255, but almost no TV's can handle that. They all use RGB limited which is the 16-235 scale.
If you set the xbox to use RGB FULL, and your TV cannot handle it (most can't), that means every black or white that is outside of the scale it can recognize (16-235) will be displayed as a black or white, not in between. This means shadows and highlights are destroyed.
Check out this article, it has Q&A at the bottom
https://referencehometheater.com/201...ll-vs-limited/
BTW I have tried setting it to FULL RGB, but with no affect.