How can users manage their screen brightness on an iPhone?

Managing screen brightness on an iPhone is most effectively done through the Control Center or the Settings app under Display and Brightness. The Control Center provides a quick and accessible way to adjust brightness with a simple slider, allowing users to change the brightness level on the fly. This feature is particularly useful when users are outdoors and need to increase brightness to see the screen clearly or when they want to reduce brightness to save battery life in low-light conditions.

In addition, going through the Settings app under Display and Brightness offers more detailed options, such as enabling Auto-Brightness, which automatically adjusts the screen's brightness based on the ambient light conditions. This versatility helps users to have complete control over their display settings depending on their usage scenarios.

The other methods listed do not directly impact screen brightness. For instance, the App Store is for downloading and managing applications, while changing the wallpaper would not affect the brightness of the screen but only the aesthetic appearance. Restarting the device typically refreshes system processes but does not change the brightness settings, making it an ineffective method for controlling screen brightness.