YouTube has quietly introduced an experimental feature called pinch to zoom exclusively for Premium users, Android Police has reported. It lets you zoom into the video player and then pan around to look at different parts of the screen, both in portrait or full-screen landscape view, as shown below.
If you're a Premium user, you can try it out by tapping your profile photo and hitting "Your Premium benefits," opening the "Try new features" section and enabling the zoom function. It might take a while for the feature to kick in, but once it's active you can zoom in at up to 8x.
In the past, YouTube tested interesting features like picture-in-picture with random users and beta app testers. In 2020, though, it launched experimental features for Premium users, letting them try out new options before anyone else. Several experimental features have made their way to the Premium app, including easier playlist management and browser-based voice search. The new feature will be available until September 1st and is only supported on Android devices for now.