The reachability feature allows users of Apple's first foldable iPhone to swipe outward from either edge of the exterior display, shifting content closer to the thumb for one-handed use. This functionality is accessible through the Settings app under Accessibility > Touch.
While reachability was first introduced in 2014 for larger iPhones, the iPhone Duo's implementation slides content sideways rather than downward. The feature is designed for the device's 5.4-inch OLED display, which is comparable in size to the discontinued iPhone mini line.