You can download the CTL5 firmware from Sammobile or maybe even from Frija. For the Frija tool...check XDA Developers. Either way, you can use Odin flash the firmware to your phone. That's what I did. I never got an OTA notification. Mine is a Verizon model S20+, but I flashed the U1 (unlocked) software to my phone to get rid of the bloatware. Plus, I like the way Heya (caller ID) is incorporated into the phone app on the unlocked firmware.
Go settings. update phone. enable auto over wifi.
This device: SM-G986U1, Model 7, S20+ 5G, Samsung unlocked US version, carrier Verizon.