Once the proper configuration profile has been installed from the Apple Developer Center, the new watchOS beta can be downloaded through the dedicated Apple Watch app on the iPhone by going to General --> Software update.
To install the update, the Apple Watch needs to have at least 50 percent battery, it must be placed on the charger, and it has to be in range of the iPhone.
watchOS 5.1 includes support for Group FaceTime, with Group FaceTime calls able to be answered in an audio-only capacity on the Apple Watch. Group FaceTime allows you to chat with up to 32 people at one time.
The watchOS 5.1 update also brings a full-screen new "Color" watch face option for the Apple Watch Series 4, with users able to choose between multiple shades. There's also a filled-in circular color option for older Apple Watch models that joins the standard Color clock face.
Should additional new features be found in the second beta of watchOS 5.1, we'll update this post.