Will exercise enhace breast size and what is the exercise or eating soy milk and soy cheese enhance breast size too? im 21

These activities: Will not increase your cup size. If you gained weight it is likely that a certain amount would go to breast (but no guarantee). If you develop your pectoralis muscles your breasts will lie differently on the chest (usually in a manner that is attractive to most).

Upper body...: Upper body exercises that will strengthen and enlarge the pectoralis major and minor will help to give the impression of a larger bust. There aren't any exercises to specifically increase breast tissue, since they are modified sweat glands packed in fat.