A few settings make a big difference on the Series X.
Quick Resume
Keep several games suspended and switch between them in seconds. Pin your favourites so they stay in the Quick Resume list.
Expand storage the right way
Series X games need internal storage or an official Storage Expansion Card to play. A USB drive can store them and play Xbox One and older games.
Turn on 120 Hz and VRR
In Settings > General > TV & display options, enable 120 Hz and variable refresh rate if your TV supports them.
Auto HDR and FPS Boost
Auto HDR adds HDR to older games, and FPS Boost raises the frame rate of some backward-compatible games. Both are in each game’s compatibility options.