Almost as if on purpose, OnePlus begins their rollout of OxygenOS 4.0 to the OnePlus 3 and 3T, this new year. The 4.0 brings the Android Nougat 7.0 upgrade to these two phones. There are also a number of changes including a new notification design, multi-window support, and a better Settings menu. OnePlus also presents to the table, options for the status bar icon and improved shelf customization.
This rollout began on December 31, and a broader campaign is in the works for the future. Also, you have a OnePlus 3T, you can get ahead of the game thanks to the OxygenOS Open Beta 1 (N). As a reminder, flash your own phones at your own risk. In addition, note that as one of the first beta programs for the 4.0, expect a lot of potential bugs. Check out the official forum page for the OxygenOS 4.0 for more info.