A large software update has started rolling out in India this morning for the S21 series ( Monday 29th March 2021 ) it is around 1GB in size with April 2021 patch and firmware version G99xxXXU2AUC8. Camera improvements, overall performance improvements. Changes to portrait mode.
I haven't received it myself so far, however it will be available in other countries very soon.
Edit: its literally just finished now buddy. I only started installing it a few minutes ago. I'll play around for a few hours after it's done and come back and let you know. Or I'll do my very best to, I might forget 😬😄 I've logged camera, Biometrics, One UI home, Lock Screen, Messages and Phone versions before to compare versions afterwards.