Strings of code show Swipe to Switch Watch Face returning in watchOS 10.2
You can set up watch faces to swipe to by going to the Watch app on your iPhone, tapping the Face Gallery tab, and creating alternate watch faces. You can make several different watch faces for different occasions including some functional faces with plenty of complications for the workday, a more formal watch face for upcoming holiday parties, and other watch faces for other events including your workouts.

You can find an Apple Watch watch face for any occasion on the iPhone’s Watch app
With a quick swipe, you can change your watch face to have a watch to fit any occasion without having to own more than on timepiece. By setting your Apple Watch to enable “Swipe to Switch Watch Face,” you can quickly go through the watch faces you’ve set up by swiping your Apple Watch display.
It isn’t clear why Apple decided to do away with the feature in the first place since swiping the screen in watchOS 10 doesn’t do anything. However, the company must have received enough feedback from Apple Watch users missing this quick and easy way to change the watch face on their smartwatch.