How much time compression does the Camera app's time lapse mode apply?
According to this blogpost from 2014, when the feature was released with iOS 8, the speed adjusts based on the length of the recording:

&lt;10 minutes -- 2 frames every second -- 15x

10 minutes to 20 minutes -- 1 frame every second -- 30x

20 minutes to 40 minutes -- 1 frame every 2 seconds -- 60x

40 minutes to 1 hour 20 minutes -- 1 frame every 4 seconds -- 120x

1 hour 20 minutes to 2 hours 40 minutes -- 1 frame every 8 seconds -- 240x

Every time the recording length doubles, the frame capture time and playback speed doubles as well. The author tested up to 8 hours and mentions that Apple referred to a 30 hour time-lapse...