Anyone with an Apple TV HD or Apple TV 4K can now download tvOS 15.3.
The software should automatically be downloaded to a Apple TV HD or Apple TV 4K.
If you haven’t already enabled automatic updates, you can download the software by heading to Settings > System > Software Updates > Update Software. Right the button to update software is the toggle switch to turn on automatic updates.
There are no known new features. The update focuses on small bug fixes and other improvements.