In the past few years, we have seen plenty of trippy fractal and optical illusion apps that run on iOS devices. Peder Norrby’s new app, TheParallaxView, is also worth a look. It creates illusion of depth with 3D head tracking on iPhone X. No external devices needed to pull this off.
The positions of the eyes are tracked using ARKit face tracking. As the developer explains, to get the most realistic stereo effect, you will need anaglyph or active glasses.[Source]