When you open up your multi tasking that shows all the open apps in card format tap on the icon at the top and if the app can be put into split screen it'll have the option to tap on it.
🌈 Stay Safe & Stay Alert. 🌈
Current Phone ~
Samsung Note 20 Ultra 5G SM-9820 _256Gb SnapDragon 865+
Samsung One Ui 2.5/ Android 10.