Samsung
Turn On/Off Dark Mode auf Samsung
Dark Mode replaces the bright white system background with a dark one across the interface, home screen, and most native apps. On Samsung phones with an AMOLED display, this can noticeably reduce power draw because dark pixels use less energy than light ones.
The setting lives inside the Display menu, separate from Blue light filter or adaptive brightness. If your screen still looks too warm or too dim after enabling Dark Mode, the issue is likely one of those other settings, not Dark Mode itself.
To switch it on or off: go to Settings ➔ Display ➔ choose Light or Dark.
You can also set Dark Mode to switch automatically at sunset or during custom hours from the same screen, so you do not have to toggle it by hand every day.
Some third-party apps ignore the system setting and keep their own light interface regardless of what you choose here. That is a limitation of the individual app, not of the Samsung setting.