Actually, not really. The average soldier had to be of generally larger stature than the average person, to have the arm's reach to be able to work with the musket, especially work with the ramrods. But the German states, especially those allied with Prussia, tended to select grenadiers for their experience and aggressive temperament, rather than stature (Frederick William's Lange Kerle notwithstanding).
Of course, colonial broadsides painted the German troops to be monsters. But most accounts from the Revolution indicate that where our side came in contact with them, they tended to be more professional, and to adhere to "civilized" rules of war, moreso than the British. Continentals often expressed surprise that they weren't the ogres they had been painted to be.
Prost!
Brad