Step 1: Open Control Center by swiping down from the top right corner of the screen.
Step 2: Hold your finger on the brightness slider in Control Center.
Step 3: Drag the brightness slider left or right to lower or increase the screen brightness.
Step 4: Let go of the brightness slider when the desired brightness is reached.
Step 5: The screen brightness level will adjust accordingly.
Step 6: Close Control Center by swiping back up or tapping outside the menu.