There are very few Custom Roms Available For Realme X2 but the Latest Lineage OS 16 ( Based on Android 9) is very stable for daily use and I was quite impressed how smooth and snappy it is. Make sure you subscribe to the channel as we shall do a sequel on this topic. Lineage OS 17.1 Based on Android 10 is almost ready to roll out in very soon for Realme x2 likewise Havoc OS 3.3 based on Android 10. There are few other Custom Roms already available too like CrDroid (based on Android 9) and Oxygen OS port.
WARNING: If you are A Beta Tester for Realme UI or you just upgraded to Realme UI (Indian/China Variant) Without unlocking bootloader, please note that there is NO WAY TO UNLOCK BOOTLOADER IN REALME UI for Realme X2, DO NOT EVEN Try to do it you will end up bricking your device.
You just have to wait for Realme to come up with their official unlock method
If you are on Color OS and still want to unlock the bootloader, you can do so, It won’t stop you from getting Realme UI either…