. Theres two main touch technologies the modern iphones use. Apples "3D touch" which provides a functionality to recognize "force touch" gestures. Its not really a "how hard is this press" thing, Its more a forceful touch vs regular touch thing, although I believe a more nuanced reading must be possible on account of art apps that recognize pressure. Theres also the haptic technology that provides a degree of feedback to certain touches via a small motor mounted under the touch screen that viabrates. You know the fingerprint reading button on the pre face recognition phones? Totally not a button, its an illusion caused by haptic thats so realistic its almost impossible to convince your brain the "button" isnt depressing. But thats a little off topic.
The amount of apps that use force touch isnt' high, partly because its not clear apple will continue to support it. It was removed from the latest iPhone XRs leading a lot of developers to suspect its being phased out. Honestly for the uses apple where using it for, it was bit of a gimmick. and yeah, it was never successfully implemented on the iPad