After selecting an element or multiple elements, a reference point locator appears  . Click and drag its small square (i.e., handle) to adjust the size of the shape.

If you want to make precise scaling adjustments, please click the sidebar to expand the "Basic Transformation" settings panel and set its width scaling factor, height scaling factor and uniform scaling factor. You can also click the element and enter the width and height in the toolbar above .

If you want to make the width and height of a primitive or multiple primitives equal based on the primitive itself, you can select the primitive or multiple primitives and choose the menu "Transform" > "Set to Square" to achieve it, as shown in the figure