Although only present on iOS devices, Android users can bring up this dark YouTube mode feature using a special trick. Unfortunately, this trick can only be used on Android that has been rooted.
Activate the Dark Mode YouTube AndroidUsing the method of changing data in the sharedpref file, you need the Preference Manager application that can be downloaded for free on the Play Store. Download and install the application on Android.
Open the application and don't forget to give root access, then search YouTube on the list (if there is no activate show system apps). Then open youtube.xml and search with dark keywords. Change the two values from false to true.
If there is no value, you can add the Boolean type value manually (theme_dark_app and theme_dark_watch_panel) and change it to true. After changing, click save and force close the YouTube application.