Method1:
a) Touch the icon at the bottom right corner of the screen, your recently used applications will be displayed.
b) If the current application supports split screen, there will be a split screen operation prompt at the top of the screen: “Swipe to corner to trigger float window/split screen”. Follow this prompt.
Method2:
Go to “Settings” -> “Button & gestures” -> “Gestures” -> “Split-screen gesture”, then in the home screen or applications supporting split screen, swipe up with 3 fingers on the screen to activate split mode.