Samsung releases a new Good Lock Module, MultiStar. Can force any application to splitscreen and keep both windows active. (ie: netflix in splitscreen, or play 2 games at the same time). :
How to use Samsung MultiStar to try real multitasking - Android Authority
Samsung Good Lock (2020) One UI 2.1 - MultiStar - YouTube
Samsung Good Lock 2018 gets new MultiStar module for improved split-screen multitasking [APK Download]
Samsung's MultiStar Module for Good Lock Takes Split Screen Multitasking on Steroids
the module to use the multi-window in Samsung - iGamesNews