Yes—on iPhone you can adjust exposure while shooting, including in the built-in Camera app. After you tap to set focus and metering, an exposure control appears; dragging up or down lets you brighten or darken the image.

Some third-party apps also claim exposure adjustment, such as Camera+, but older iOS camera APIs limited direct manual control. In those cases, an app may be adjusting the image through software rather than offering true camera-level exposure compensation.

A simple built-in method is to tap on the part of the scene you want the phone to meter from. Since focus and metering are linked, choosing a brighter or darker area will affect the overall exposure. On supported iPhones, using the on-screen exposure slider gives you more direct control over that brightness adjustment.