The Youtube team announced support for full-screen vertical video for all devices running on iOS
So now no annoying black bars on the sides of the screen while watching your favorite channels, the video player automatically adapts to the video format that the user views. The feature is clearly demonstrated on the hypha below. The expected step on the part of Google, previously the team YouTube has added support for the format 18: 9 and 16: 9 specifically for frameless smartphones.
The update is already available for download at the AppStore via this link.