Here are the latest open beta builds for the OnePlus 6 and OnePlus 6T.

Changelog

• System
  • Updated Android Security Patch to 2019.04
  • Improved network speed display
  • Supported shortcuts to access corresponding interfaces in Quick Settings
• Quick reply in landscape
  • Supported quick reply in the notification bar
• Launcher
  • Added tutorial in shelf
  • Added Parking location feature
  • Improved page Indicator to mirror Icon pack

Please keep in mind that this is beta software.

Please note:

• If you have already flashed an Open Beta (you are currently running the latest Open Beta), you will receive this new build as an OTA.
• If you are not running open beta software and would like to, please refer to the flashing instructions and the full ROM on the downloads page here.
• Once you migrate to the beta path, you will continue to receive Open Beta OTAs. You will no longer receive the regular Official Stable OTAs.
• Moving back to the Official OTA path from the Beta path will require a full install and clean flash (full wipe of all data and cache).

Source