This Seeking Tech guide will show you how to turn off cross-platform matchmaking in the Xbox One, Xbox One S, Xbox One X, Xbox Series S and Xbox Series X versions of MultiVersus.
1. To start off, open the Settings menu of your Xbox.
2. From there, you need to select Account, and then Privacy & online safety.
3. Over the next several screens, go to Xbox privacy > View details & customize > Communication & multiplayer.
4. Finally, set the “You can join cross-network play” setting to Block.
5. You then have to reboot the game. You can do so by opening the Guide menu and then quitting MultiVersus. Afterwards, launch the game again.
Crossplay should now be disabled.