Realme has just begun rolling out its September 2021 Security patch for Realme C21 via OTA.
Realme C21 was released on 05th March 2021 with Android 10 out-of-the-box.
This smartphone is in the budget range and even though it came in with Android 10, it got updated to Android 11 recently in August 2021 with improved features at a time when Android 12 is fully baked and anticipated to roll out well before the end of the year.

Source>>>Realme Community
| Android OS | Update | Release Date/Status | Estimated Months |
| Android 10 | Out-of-the-box | March 2021 | Nil |
| Android 11 | First OS update | August 2021 | 5 Months |
| Android 12 | Second/Last OS update | Expected | – |
The Realme C21 came with Android 10 out-of-the-box and It recently got an Android 11 with Realme UI 2.0.
It's highly anticipated that it will get its possibly last/major update Android 12 soon.
Check out :
The Realme C 12 came out with Android 10 out-of-the-box.
Once the update is available on your device, you can head over to Settings >> About Phone >> Software Update section to update your Realme device with the latest security/software update.
For more Realme Android updates please download our Android App – Available on the Play Store