After being released OxygenOS Open Beta 35 and Open Beta 26 for OnePlus 3 and 3T, the OnePlus team just released OxygenOS Open Beta 9 and Open Beta 7 for OnePlus 5 and OnePlus 5T. The update includes double tap to lock screen support, improve App drawer search history, alongside general bug fixes. The update is now rolling out through OTA for beta participants.
Recently, OnePlus released stable Android 8.1 Oreo based OxygenOS 5.1.0 update for OnePlus 5 and 5T, while the beta build allows users to try out new features before they arrive for everyone. For example, the OxygenOS Open Beta 9 and 7 bring double-tap to lock screen support to both devices.
Changelog:
Supported double-tap to lock screen
Improved searched history for App drawer
Optimized scanning logic for large files in File manager
If you would like to install OxygenOS Open beta manually and want to enjoy the latest features of Android 8.1 Oreo based OxygenOS Open Beta 9 and 7 on your OnePlus 5 or OnePlus 5T, then you can download and install the full ROM.
You can install the update via stock recovery as described here. However, keep in mind that since this is a beta OS, it is possible you will run into bugs and other instabilities. (Source – OnePlus)