The reason why you can't grab multiple sides of a rectangle with handles by default in CAD is that they are not modified together.
Except for the STRETCH command
If you want to stretch each side of the rectangle with a constant offset, you can use the basic STRETCH command.
As gif below
But for a simple rectangle, you can get information on each corner like BIGAL's code
and you can add some loop code for each rectangle to make it look like it's stretched together.
In this case, have to select the target rectangle anyway, so I'm not sure if there is a benefit compared to not using STRETCH.
So, tell us 'detail' about your need.
And it is more common to use BLOCK to modify multiple objects at the same time
because If only one BLOCK is modified, all of them are modified.