OnePlus has released the OxygenOS 11 public beta firmware to the OnePlus 7 and 7T series so those wanting to give Android 11 a try as quickly as possible can now do it.
There are some known issues you should be aware of. Brightness adjustment might lag in some cases, some Bluetooth-connected devices may not produce sound occasionally, there’s a chance of higher power consumption and decreased stability.
In turn the devices will get the new overhauled OxygenOS 11 with host of features (new icons and UI, ambient display, new Shelf interface, new camera UI, features and HEVC codec support, etc).
You can find the download links in the source links below. You need to have a supported unlocked device, download the ROM upgrade zip, copy it in the root folder of the phone, navigate to settings > system > system updates > local upgrade on the phone and follow the instructions.