In addition to various tweaks and fixes, the new Open Beta builds for OnePlus' handsets integrate the all-new OnePlus Launcher 2.1 app that comes with support for Weather and Calendar dynamic icons, and much more.
https://www.notebookcheck.net/OxygenOS-Open-Beta-19-for-OnePlus-3-and-Open-Beta-10-for-3T-now-available.232036.0.html