To make your iPhone screen dimmer or bright from Control Center, open the Control Center then drag the brightness indicator up.
From a Home screen, navigate: Settings > Display & Brightness.
If your iPhone is running iOS 13 and higher, from the APPEARANCE section, select Light or Dark.
Tap the Automatic switch to turn on or off .
For iPhone 4 / 4s / 5 / 5c, tap the Auto-Brightness switch to turn on or off.
When enabled, tap Options to schedule times to change appearance automatically.
From the BRIGHTNESS section, slide the brightness indicator left or right to adjust.
Tap the True Tone switch to turn on or off.
Automatically adapts color and intensity for iPhone 8 and newer models.
To automatically shift the colors on your display after dark, refer to Night Shift.