Select the objects you want to resize. How?
Right-click anywhere in the selected objects and select Make Same Size. Three options are then available. Choose one of Height, Width, or Both (height and width).
All objects are resized according to the object last selected.
TIP: The object with the white handles controls the size that is applied to all objects. If the object you want to use as the size model for other objects is not selected, click again on that object (all other objects will stay selected).