As well as the usual method of selecting Video from the menu strip below the viewfinder, iPhone 11 series users can also simply press and hold the shutter button, then release it to stop recording.
In October 2019, Apple released iOS 13.2, which added another camera app function for iPhone 11, iPhone 11 Pro, and iPhone 11 Pro Max: The ability to change video resolution and frame rate on the fly.
Next time you shoot video using the Video mode found in the menu strip below the viewfinder, notice the video resolution and frame rate separated by a dot in the top-corner of the screen.
If video quality is set to 1080p in Settings -> Camera, you can tap the resolution in the Camera interface to flip between HD (1080p) and 4K. If it's set to 720p in Settings, tapping the format flips between 720p and 4K.
When shooting in 4K, you can tap the frame rate to switch between 24 (for low light), 30, and 60fps. If you shoot in HD (1080p) format, you can flip between 30 and 60fps, and when shooting in 720p, the frame rate is limited to 30fps.
Previously, changing these video settings was only possible by going into Settings -> Camera, so the ability to adjust them from the Camera app is a boon, especially when you want to capture something at a moment's notice.