how to turn a diamond into a square?

suppose I start with a rectangle, and extrude and scale a face down, so I have a smaller rectangle inside the larger. Is there a quick way to turn the rectangle into a square (even the edge lengths, turn all the angles into 90 dgrees) I click smooth, but that just shrinks it, doesn’t even out the edge lengths?

Quick and dirty way is to select opposing edges and scale it up or down to its normal axis on plane. Turn on the Edge Length, so that you can match the length to the other two edges.

maybe look at the cast modifier