Xiaomi
Open Split Screen via Recent Apps auf Xiaomi
Split screen on Xiaomi phones runs through the Recent apps overview, not through a separate settings menu. The system needs to know which two apps should share the display before it activates multi-window mode, so the trigger sits inside the app switcher itself.
Open Tap on Recent apps ➔ Tap and hold an app ➔ Tap on Split screen ➔ Select the second app to place two apps on the screen at once. Once both apps are visible, Drag the border to resize the contents shifts the space between them, useful when one app needs more room, for example a video call next to a note-taking app.
Not every app supports this mode. Apps that block resizing or run in full-screen-only mode will not show the Split screen option in the app card menu, and MIUI simply skips that entry instead of showing an error.
To leave the mode, Tap the Home button to exit closes both apps from the split view and returns to your home screen. If you only need to check something briefly, use a floating window instead of split screen, since it keeps the second app small and movable rather than pinned to half the display.