Asymmetric entity offset?

Hello

Wouldn't there be a function like offset but which allows margins of different widths (for lines) or even variable (for curves)?

In this case, it would be to get a kind of frame from an old Polaroid photo, 3 equal margins and 1 wider at the bottom, simply from a rectangle.

Currently I am forced to create the other rectangles myself, to align their center vertically, and to dimension at least 2 margins and 1 length. Repeated 2 times here with the rectangles under construction.

decalageAsym

Or do you have another method to do this?
Thank you.