Some apps like TikTok and Netflix do not support split screen.
Today i'm going to show you to enable split screen for any app on Android 10
Steps:
To do this go to settings
Scroll up
Then tap on "About phone"
Scroll up
then tap on "Build number" 7 times.
This will enable "Developer option" on your phone.
Now draw your pattern to unlock your phone
Now go back
then tap on system
Tap on advanced
then tap on developer options.
Scroll towards the end of the page
Then enable the button next to "Force activities to be resizable"
After that you will need to restart your phone
Now my phone has been restarted
select an app let's say TikTok
Tap and hold the bottom of the screen whilst dragging it up then release
Tap on the Tiktok icon on top of Tiktok app
As you can see i can now use split screen with Tiktok app.