OnePlus 6 runs OxygenOS Open Beta 1 starts getting the OxygenOS Open Beta 2 OTA update, which weighs around 136MB. Devices running on the stable OxygenOS (Android 8.1 Oreo) can also download and install the update manually and enjoy latest Android 9 Pie and its features right now.

What’s new in OxygenOS Open Beta 2? Android 9 Pie brings several new features like gesture navigation, brand new UI, and other new features. In addition, OnePlus also included its own customization features to the OxygenOS Pie build. Accent color customization, new ‘Do Not Disturb’ mode with adjustable settings, new Gaming Mode 3.0, etc are few examples. If you have not received the OxygenOS Open Beta 2 OTA notification yet on the device, you can use the Oxygen Updater app to get the update right now without waiting for the OTA. Download OxygenOS Open Beta 2: Alternatively, you can download  full update package (1.5GB) from here and flash it manually. Follow this guide for manual installation instruction. (source)