Samsung
Schedule Dark Mode auf Samsung
Dark Mode on Samsung phones does not turn itself on automatically until you enable a schedule. Without one, the display stays in whichever mode you last picked, even after sunset or in a dark room.
Samsung offers two automation options: a schedule that follows sunset and sunrise based on your location, or a custom schedule with times you set yourself. The custom option is useful if your sleep hours do not match daylight hours, for example on night shifts.
To set it up, go to Tap on Settings ➔ Tap on Display ➔ Tap on Dark mode settings ➔ Enable Turn on as scheduled. From there, choose Sunset to sunrise or Custom schedule. If you pick the custom option, set the Start/End time that matches when you want Dark Mode active.
Once scheduled, the phone switches modes on its own and you no longer need to toggle Dark Mode manually from the notification panel. If Dark Mode still does not switch as expected, check that location access is granted when using the sunset-to-sunrise setting, since the phone needs it to calculate local times.