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.
macOS Catalina Now Available
Apple Seeds First Beta of iOS 11.2.5 to Developers
Registered developers can download the iOS 11.2.5 beta from Apple's Developer Center or over-the-air once the proper configuration profile has been installed from the Developer Center.
It's not clear what new features will be included in the iOS 11.2.5 beta, but as a minor 11.x.x update, it is likely to focus primarily on bug fixes and security improvements rather than major outward-facing changes. It's not clear why Apple has skipped several numbers to release an 11.2.5 beta.
We are still waiting on two major iOS 11 features that have yet to be introduced, though. iCloud Messages and AirPlay 2 have not yet been fully implemented and are likely to be added in an upcoming beta.
Prior to iOS 11.2.5, Apple released iOS 11.2, which brought Apple Pay Cash, Apple's new peer-to-peer payments service, plus faster 7.5W wireless charging and a long list of bug fixes.