Maybe I am a bit too late to the discussion and your problem has been resolved.
You can actually check per-application VRAM usage in the Windows Task Manager
Just Go Select columns and find GPU Memory.
The usual VRAM-hogs are the chromium based apps like Navigraph Charts and Volanta etc.
On the other hand, the 3080 10G is fine most of the time with Texture Resolution set to High on DX11 in 1440P, however this is not the case in the DX12, I have to lower either TLOD or Texture Resolution to Medium.