There has been a lot of confusion regarding the One UI 2.1 update for the Galaxy Note9. Samsung rolled out the One UI 2.1 update with some Galaxy S20 features to the Galaxy S10 and Note10. The company never officially mentioned that it was working on bringing One UI 2.1 to the Galaxy Note9, though some reports claimed otherwise.
A Samsung Members community moderator has now apparently confirmed that the One UI 2.1 update for the Galaxy Note9 will arrive in June 2020. Some of the Galaxy S20 features that will be available on the Galaxy Note9 post the One UI 2.1 update includes Single Take, Pro video mode, Music Share, Quick Share, and more.
Samsung had launched the Galaxy Note9 in the second half of 2018. The device launched with Android 8.1 Oreo and has since then received two major updates in the form of Android Pie and Android 10. It is likely that the One UI 2.1 update will be the last major update for the Note9. After that, Samsung is only expected to regularly roll out security updates for the device.
If you own a Galaxy Note9 and cannot wait for the official One UI 2.1 update to arrive, you can always install a custom ROM on the device that brings many of the Galaxy S20 features to it. This will require you to root your device and install a custom recovery on it though.