Twrp flashing

1) Can I flash stock ROM 4 files (bl, ap, cp, csc) in my Samsung on 5 (SM-G550FY) using twrp, if yes, please tell me what is the right process for this method and which is d best custom rom for this model
2) is there any other custom recovery compare to TWRP which I can flash in my old model Samsung galaxy on5 (SM-G550FY)
3) IS THERE ANY EASY METHOD TO FLASH CUSTOM RECOVERY IN MY GALAXY S 20 FE 5G (SM-G781 B/DS)
Thanks