Hi Mark,
I have searched the “Make Square” plugin, but I can find it at all.
https://nitro4d.com/product/nitrocycle/
If you check out the NitroCycle, while it only one polygon is selected, and the Round parameter is set to zero, you might come very close to a square. Again, it works just for a single polygon.
Other than that, the Instant Mesh will perhaps help here
https://www.cineversity.com/vidplaytut/turn_any_object_into_hexagons_with_instant_meshes
Of course, a whole mesh into squares would alter the shape drastically, hence why I tried to find the plugin to see what to expect in the first place.
I would encourage to write to the author of the plugin, to produce a Python script.
All the best