YoutubeVanced, A modded version of the official YT application offers you a number of YT premium features without any cost. Among them,

Built-in Adblocker
Background Playback
Force HDR Mode
Override Max Resolution
Pinch to Zoom For All Devices
Secondary Themes
Picture-in-Picture Video
Repeat Videos
Preferred Resolution & Speed
Swipe controls for Volume & Brightness are prominent. Hope this app will be one of the useful apps for you