no, i install the lasted rom with a clean install and got the twrp after install
when you flash the rom, when it ask to reboot it ask something about recovery and you need to choose the option do not install
i update from 8.6.20 to 8.6.21 and didn't need to restore nothing, i did a firty flash and everything is ok, but if you are in a diferent version a clean intall is better
after install the zip file i not sure if there is already intalled manager, but i force the installation,
and when i open magisk manager ask me to update some files
i try this steps:
install magisk 16.4
reboot phone and install magisk manager 5.7.0
update magisk files
reboot phone again
and i can edit files and already got *no-support-for-this-app-on-this-forum* working on phone