The stable update for Android 9.0 comes in the form of OxygenOS 9.0 and offers new features such as the "Do not disturb" mode updated, a game mode 3.0 with a text notification mode and a notification for third-party calls and the support for color customization. According to the changelog posted by OnePlus, the update includes new Do Not Disturb (DND) mode with adjustable settings and a new Gaming Mode 3.0. OnePlus has also conformed that they will be bringing Android P update to the OnePlus 5/5T and OnePlus 3/3T for users to enjoy new features on their devices. Most manufacturers takes at least a couple of months to release the new update, and majority of the smartphones do not receive the latest updates. Outside of the Pixel lineup, the only smartphone that has gotten the update so far is the Essential PH-1, so this is definitely a good thing for OnePlus users.
Announced in June this year, the OnePlus software maintenance program guarantees two years of Android updates and three years of security updates on all OnePlus phones, starting with OnePlus 3 onwards.
OnePlus also confirms again the OTA will be a staged rollout.
Once the update reaches your device, you should be getting a notification.
The file size of the OxygenOS 9.0 update on OnePlus 6 is approximately 1521 MB, although it may differ on some units. Going by the strategy of the company, its seems that OnePlus will most likely discontinue the OnePlus 6 soon after the launch of the upcoming OnePlus 6T.
OnePlus confirmed that since it's a phased out update, some users will receive it today, while other might have to wait for a few days. As the update is being sent out randomly to users and is not region specific, using a VPN to download the OS wouldn't be helpful.