There is no lower age limit for children and calisthenics. Children can start doing low-level calisthenics movements and gradually progress up through more challenging variations as they grow in strength and confidence
Calisthenics have been shown to benefit people of all ages and fitness levels. The trick, however, is choosing the exercises that correspond with your current fitness level. If you're not sure if calisthenics are right for you or are new to bodyweight training, experts recommend beginning with the basics.
Calisthenics uses your bodyweight and involves compound exercises. It requires a lot of movement, making it better for losing weight and defining your muscles. With weightlifting, you use external weights like dumbbells. It involves isolated exercises that increase the size of a muscle group.