I just ran across an article and demo from earlier this month, that uses the iPhone X's TrueDepth Camera to Conjure 3D Illusions as shown in this video.
The author even published the demo as a free iOS app, so you can download it and give it a go.
These techniques are not new: viewpoint dependent rendering, where a 3D image is rendered on a flat (monoscopic or stereoscopic) display is the basis of a myriad of research and commercial systems. CAVE systems (VR systems formed by projecting graphics onto 3 or more walls and floors of a space to create the illusion of being inside the space) typically rely on those techniques (even though they limit the system to one viewer at a time). 3D movies and 3D TV's would do this if they could, but you can only render convincingly for one viewer at a time.
A version of these techniques went viral on youtube back in 2007, when Johnny Lee showed how to do an inexpensive version of these techniques using a WiiRemote for tracking. His demo was pretty slick (although a community of graphics and VR researchers were frustrated that people got the impression from his video that he invented the idea). Here's his video, it's pretty similar idea.
I love these illusions, in a CAVE or a handheld.
But seeing it on an iPhone screen in the palm of your hand is pretty cool. Give it a try!