How Do I Play Rocket League in Split-Screen on Xbox?
You can play Rocket League with a friend locally. To get started, you will need two controllers to activate the split-screen feature.
Both players need to have full Xbox accounts. Guest accounts cannot be used to access online features, so split-screen won't work. You can review more details about this change here: Why can't I use online features in Rocket League when using a guest account on Xbox?
Connect all controllers
Player 2: Log in with Player 2's Xbox account
Launch Rocket League
Player 2: Press the Menu button on the 2nd controller
Up to four total players can join
Player 2 will then join the party and play any Offline or Online mode together.