A small change in the position of individual teeth doesn't have a significant effect on the appearance of the face. Still, depending on the treatment method and the way space is found to straighten crooked teeth, some change can be expected. For example, a canine in crossbite on one side makes the lower lip stick out asymmetrically on that side, and treatment restores the symmetry of the soft tissues.
This answer is for general information. Your own case needs an examination by an orthodontist.