Nope. The scale changes with magnification only, which is held constant here. It is the plane of focus that moves (slightly in the range of a few tenths of a mm).
There are other posible modes of stacking in which the magnification changes (for example, a camera uses built-in AF-based stacking), and then the scale, if required, has to be computed from the main plane of focus for the subject. Typically those approaches are used when you stack a large scene to get excessive depth of field, such as in a landscape. I don't think the 'image scale' concept is of much importance in such circumstances. If the scene is a "miniature landscape", however, then one might put a scale bar into the scene as a final step.
