This Seeking Tech guide will explain how you can turn off or turn on cross-platform matchmaking in Sonic Racing: CrossWorlds.
Refer to the video and text guides below:
Step 1: Go to Main Menu.
Step 2: From there, select Extras.
Step 3: You then need to select Options.
Step 4: Afterwards, switch over to Online Settings.
Step 5: You should then be able to set Crossplay to On or Off.