For OnePlus 9/9 pro unlock bootloader, install TWRP and Magisk -> please follow this Instructions:

https://www.getdroidtips.com/twrp-recovery-oneplus-9-9-pro-root/

root hide

1-Enable Zygisk in the Magisk app’s options, do the same for the Denylist

2-Configure the Denylist with the apps you wish to hide root from

3-Install Universal Safetynet Fix https://github.com/kdrag0n/safetynet-fix/releases and reboot

That should be about it for now