every unit is linked to an actor. and most actors are linked to a model.
you can change the scale of an unit in data editor. find the unit actor, find the field scale and change it to w/e you like ( 0 = 0% and 1= 100%; double size = 2).
alternativly the models also have a field with scale.
click on the unit in data editor, the linked actor and model should be shown on the left
don't forget to give reputation :d