How do I resize a rectangles width while keeping the same skew

[winged dew]

When I skewed a rectangle, I cloned it to make a square as well, but when I change the width, the skew changes based off the size, any way to change this?

[drowsy carbon]

It would be better with an example, but skew will follow moves from left o right and top to cottom. In that sense it is proportional.
If you want to manage without it moving on both sides, you need to use the free transform

Unless I misunderstood what you are asking