The Custom Block Editor is launched with the command _EDITCUSTOMBLOCK or after a double-click on a block. You can use it to modify any block reference and also make them parametric in size and shape.
The contextual ribbon includes features to combine special grips and actions such as Move, Scale, Stretch, Rotate, Pattern, or Mirror. You may, for example, create a custom block whose size can be dynamically adjusted with a grip you can stretch.