First things is,your smartphone already have a new system update from samsung atleast One Ui 1.0 and above,this is because a new system interface have a "DARK MODE".You must turn on this mode and then,all apps can change theme from "light to dark".Depents to interface system support "all apps to dark mode or not".Not only that,as we know it samsung is "AMOLED SCREEN MANUFACTURERS",this also depents to phone support amoled screen.My conclusion is,when you have a phone samsung which support amoled screen and you turn on dark mode,all black content is displayed on the screen, the pixels will be turned off and only live pixels will be turned on for content that does not have black, this is because amoled screen not have a light background.Also your use wallpaper black colour or so on,good luck SAMSUNG GALAXY USER❤
