Realme has started rolling out September 2021 security patch for Realme C12 devices, just like Realme C15 September 2021 Security Patch this update is just a security patch.
Realme C12 released on 14th of August,2020 with Android 10 out-of-the-box.
Recently the device also got August 2021 parch in September with minor improvements in the system. Realme C12 got its android 11 update with Realme 2.0 this year in July.

Source>>Realme community
| Android OS | Update | Release Date/Status | Estimated Months |
| Android 10 | Out-of-the-box | August 2020 | Nil |
| Android 11 | First OS update | July 2021 | 11 months |
| Android 12 | Second/Last OS update | Eligible | Unconfirmed |
The Realme C12 was released with an Android 10 in August 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.
The Realme C12 was released with an Android 10 in August 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.
The Realme C12 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