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 Second Beta of iOS 12.4 to Developers [Update: Public Beta Available]
Registered developers can download the new iOS 12.4 beta from Apple's Developer Center or over-the-air once the proper configuration profile has been installed from the Developer Center.
There were no new features discovered in the first iOS 12.4 beta, so it's not entirely clear what's coming in the update. As a more significant 12.x update, it's possible that the update is focusing on a feature that's not yet available - the Apple Card.
Apple is planning to release the Apple Card in the summer, so iOS 12.4 could be the update that prepares the iOS operating system for that launch, adding hidden features that will be unlocked when the update becomes available to the public.
If we find new features in the second beta of iOS 12.4, we'll update this post.
iOS 12.4 may be one of the last updates to the iOS 12 operating system as Apple transitions to iOS 13, which is expected to be introduced at WWDC in June.
Update: The second beta of iOS 12.4 is also available for public beta testers.