It could be done fairly easily in Xara with the anime.js library.
Remember a browser only has around /5 to x5 zoom.

What I might to is have an image that you can scale as above to explore any part at any such scale.
When bored, one could press a key I for In and O for Out. The browser zoom would slowly rest back to 100% will following a SVG path to the 'portal' and then a deep dive into that image using CSS scalie and a fade into the next image where you can again pan and zoom to explore.

If it is fully automatic, it is just a zoom carousel.
If you had a stack of 50 images and shuffled them then the different SVG paths would at least make the travel varied and less boring.

Acorn