AT&T started pushing Android Oreo to the Galaxy S8 units on its network two days ago and now the Galaxy S8+ is also getting a taste of the new OS. The company issued a support page on the software update to Oreo 8.0, revealing what is new in the package.
Samsung Galaxy S8+
The build number R16NW.G955USQU2CRB9 is 1.51 GB in size and along with the new OS that has notification dots, autofill and better picture-in-picture mode, it also comes with February 1 security patch. There is also Samsung Experience 9.0 that was recently introduced along with the Galaxy S9.
You should already be getting a notification for a pending update, but if you want to do it manually, just head to System updates in the Settings menu to proceed with the new package on your AT&T-branded Galaxy S8+.