Soon after Samsung has rolled out One UI 3.0 beta in South Korea, Samsung started rolling it out the same to users in the US. Soon, the update is expected to reach Europe (Germany, Poland, the UK), India and China.
As of now, for those in United States having Samsung Galaxy S20, S20+ and S20 Ultra on T-Mobile seem to be getting the update right now, but that’s likely due to the staged nature of the rollout. Furthermore, You can use the Samsung Members app to subscribe to the beta channel and get this update. On the latest One UI 3.0 beta, you will be trying out Android 11 + One UI 3.0 ahead of other users. Moreover, while trying out the One UI 3.0 beta users should keep in mind that the beta is not free of bugs, but you have the option to roll back if the issues prove too bothersome. Just make sure to back up your data first.
Here’s a screenshot from one Samsung Galaxy S20 Ultra 5G user that lists the changelog in full. This update weighs about 3 GB and also includes the October 1 security patch.