Check how to install Magisk the first time.
There's the option to move apps to SD, which may or may not work with an App2SD app. And Adopted Storage. If the option for this is missing too, you can perform it via ADB and PC. But just like in Samsung's AS in Touchwiz roms from 6.0 up, there may be serious flaws. With official RR it worked on my S5 until the rom's maintainer changed. I finally gave up and don't use AS on any device anymore.
(AS with Touchwiz roms reserves the sd card for apps, data must fit into internal flash, along with the many apps which can't be moved. Dunce.
Another common phenomenon is a warning about insufficient memory when trying to move apps. With plenty of fee mem, of course.)