Well, I used TWRP official 3.2.3-3 coz 3-4 coz causes issue for me.
Firmware and format data isn't necessary, my step was :
Format Data - Wipe 4 Dot - ROM - GAPPS - reboot. Don't flash magisk with the rom, it'll cause issue.
If you encountered bootloop, repeat process, on ROM step immediately reboot to recovery and dirty flash ROM again then Gapps and reboot. Not necessary if you don't occur any issue.