Realme has just begun rolling out September 2021 OTA update to Realme C15 via OTA, this update brings general fixes in the system, display and phone manager.
Recently it also got the August 2021 Security Patch so we can say this update is running on August 2021 Security Patch with minor improvements to the device.
To call its September 2021 update, but this update doesn't bring the latest September 2021 Security Patch. but only minor improvements in the system
Realme C15 was released on July 28,2020 with Android 10 out-of the box.
Realme C15 got Android 11 with Realme UI 2.0 stable update in July 2021.

Source: Realme Community
| Android OS | Update | Release Date/Status | Estimated Months |
| Android 10 | Out-of-the-box | July 2020 | Nil |
| Android 11 | First OS update | July 2021 | 12 months |
| Android 12 | Second/Last OS update | Eligible | Unconfirmed |
The Realme C15 was released with an Android 10 in July 2020. Therefore, Android 11 is its first major OS update.
Hence, it is eligible for the upcoming Android 12 update and it will be its second/last major OS update. However, it is still unconfirmed.
Check out >>> Android 12 update list for Realme devices
The Realme C15 Android 11 Update with stable Realme UI 2.0 has been released with the September 2021 security patch.
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 update.
For more Realme Android updates please download our Android App – Available on the Play Store