The update can be downloaded now through the companion Watch app on your iPhone by heading to General > Software Update in the My Watch portion of the app. You can also go to Settings > General > Software Update on an Apple Watch
Your watch needs to have more than 50 percent power and connected to a charger. Like most Apple Watch updates, it could take anywhere from 30 minutes to an hour to complete, so be patient.
It’s compatible with the Apple Watch Series 3 and later.
The update fixes an issue that causes problems with third-party chargers and offers other bug fixes and improvements.
