OnePlus has today released the new Oxygen OS Open Beta 3 for the 5T.
The Open Beta 3 packs new navigation gestures that are reminiscent of those employed by the iPhone X (but not 100% identical). You can turn these on by going into Settings and disabling the navigation bar.
Once you’ve done that, the Home button is replaced by a swipe up from the middle part of the bottom of the display.
To go back you swipe up from the left or right part of the bottom, and if you want to invoke the multitasking screen you swipe up from the middle and hold.
The new build will arrive over-the-air if you’ve already running an Open Beta. If you want to step into the beta realm for the first time, then you need to read the flashing instructions here.