Night mode is an automatic setting which takes advantage of the new wide-angle camera that's in the iPhone 11 and 11 Pro models. It's equipped with a larger sensor that is able to let in more light, allowing for brighter photos when the light is low.
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Apple Potentially Working on Smart Battery Case for Latest iPhones
In previous versions of watchOS, Apple Watch had an icon that displayed a battery case with a bottom chin and horizontal camera, indicating this as the Smart Battery Case for iPhone 6, 6s, and 7. In the latest beta of watchOS 5.1.2, things have been changed and this icon now displays a battery case with no bottom chin and a vertical camera.
While far from a confirmation, this suggests that Apple could be working on a Smart Battery Case for the latest set of iPhones with vertically aligned cameras, which would include iPhone X, iPhone XS, iPhone XS Max, and iPhone XR. For previous generations, Apple never made Smart Battery cases for "Plus" iPhones, presumably because a major selling point for those devices was increased battery life sans battery case.
Unless Apple changes tune, this means we'd likely see a Smart Battery Case for iPhone X/XS. Still, the launch window for such an accessory -- if there even is one -- remains unclear.