For android 11 builds newer than 20201011-2020, firmware is included.
For android 11 builds earlier than 20201011-2020, install firmware V18.104.22.168.QDGMIXM
For android 10 builds newer than 20200323, firmware is included in the ROM and there is no need to install firmware manually.
For android 10 builds between 20200214 and 20200323, install firmware 20.1.16
For android 10 builds between 20191225 and 20200214, install firmware 9.11.7
For android 10 builds earlier than 20191225, install firmware 9.6.27
Reboot to system
Root and Magisk
As for rooting your phone, it is recommended to boot the ROM first without installing Magisk. After booting for the first time, feel free to come back to recovery any time afterwards and install Magisk 22.1 or newer for root.
Magisk publishes a special hybrid package after 22.0 version. The Magisk-v22.1.apk, for example, can have two use cases:
when installed in android system as a regular apk file, it will install the Magisk Manager app
when flahed in recovery as a zip file, it will patch the boot partition and root your device. In order for recovery to correctly identify the Magisk package, rename Magisk-v22.1.apk to Magisk-v22.1.zip and then
for PE recovery, adb sideload Magisk-v22.1.zip
for TWRP or OrangeFox, press the zip file to install
Magisk patches the boot partition to root your device, so any OTA updates or dirty flashing will restore the boot partition and make root disappear. This is normal. Flash Magisk again in recovery to get it back.