Since Android 9 Pie and beyond (Android 10 included), the way we split screen for multiple apps has changed. Instead of pressing the “Overview” button, now you have to hit the split-screen icon on the app thumbnail. For more details check out the following guide.
Go to the Overview layout, then hit the multitasking icon on the app thumbnail. Please note that some apps may not support split-screen.
Select the other app you want to run as well. Again, it has to support split-screen.
Now both apps are running at the same time in split-screen.
You may also change the phone's orientation. The apps should follow.
The guide above is based on Infinix Hot 9 Play Android 10 with XOS Launcher 6.2.0. Though other launchers can have a different interface and design language, I believe the process is somewhat similar.
Running multiple apps could occupies a lot of memory. Check out 7 Tips to Free Up RAM on Android.
