sometimes, Chinese people repeat a adjective twice to make up one word, like "胖胖的，高高的，小小的". Because kids like using these words, these words give people a cute and childish feeling. If speaker use these words, he or she probably have one of the following two intentions: The first intention is he or she want to pretend he or she is an adorable child, because of joking or other season. The second is expressing the person who be described is kind and approachable. In your practice, you use "胖胖的" describe the man who made you afraid of. The question is this word makes readers feel this bald man is pretty friendly and even cute. If you want to express this man's appearance and physique made you being afraid of him, you should use other words.