The Realme UI 2.0 update for Realme 6 Pro is now available in the beta phase. The firmware is based on Android 11. It is worth noting that this is an early access release, and it is possible that the OS could have bugs, so if you are using the device as your daily driver, it is not advisable to test the experimental software on it.
How to get early access to the Realme UI 2.0 update for Realme 6 Pro
Visit this Google Docs form, and fill in your information. Make sure your phone is not rooted. Your Realme 6 Pro should be on version RMX2061_11.A.39 to qualify for the program. You should charge it to 60% battery capacity or more, before proceeding.
Navigate to the Settings > Software Update screen and tap on the settings button in the top right corner, and select the option that says Trial version. You will be asked to provide your information, enter the required data and tap on the Apply Now button. If you did it correctly, you should see a message that reads "Success".
Now, this doesn't guarantee that you will get the Realme UI 2.0 update for Realme 6 Pro. The company says that there are limited seats available, you will receive the update if your application is accepted by Realme.
If you want to downgrade to Android 10, head to the official annoucement and follow the steps given on the page.