The Realme GT Master Edition doesn’t have Android 13. The Realme GT Master Edition has Android 11 as the phone’s operating system.
The Realme GT Master Edition has Android 11 as its operating system and Realme UI 2.0 as its user interface. And for a greater experience, the UI can be upgraded to Realme UI 3.0, based on Android 12. But, there is no scope for having Android 13 on Realme GT Mater Edition. Cause the Android 13 isn’t released yet.