The rescale command takes one parameter, “Keep Proportion” , if enabled object proportions will be kept.
First of all you need to select the objects on which you want to perform a resizing, then trigger the command in the pie-menu. The selected object(s) should now be transparent, and a bounding box with its dimensions (in mm) should surround the selected object(s).
To perform a rescale, grab one square with the controller trigger and move it to the desired position. Once the rescaling is done, leave the command with the thumb button, the selected object appearance should be back to normal.
If you select only one object you’ll be able to change the scale on every axis (depending if you have disabled “Keep Proportion” parameters), if you select more object, the proportion will be kept.