Scaling of different parts of the model without deformations

What is the easiest way to adjust glb model from the image so that it is possible to scale the upper and lower parts separately without deforming the model

If you scale top/bottom parts of this geometry, it looks like deformation.
Maybe you could select top/bottom vertices by their Y coordinate value and then scale/translate.
You could also make the deformation as an animation (while making the glb model) and then play it in between two selected frames.