Google has released the first stable build of Android 11 for the Pixel line of smartphones today (September 8, 2020). Now, OnePlus has announced that it too has such an update for its current flagships, the 8 and 8 Pro. They come in the form of OxygenOS Open Betas, the last step before a stable software version.
https://www.notebookcheck.net/The-OnePlus-8-series-now-has-stable-Android-11-based-betas.492533.0.html