We need to know more details about your question before giving you a complete answer. What grade level are you asking about? For example, Physical Education is not required at the elementary school level in California. It may be optional in some public high schools and junior high schools. It is not required in most private schools. It may be required for some college majors or career choices. It is certainly recommended for children that are overweight or who need physical activity to stay healthy.
I would ask your school directly for that information. Or your district. All districts/schools have different rules and if Physical Education is something you or your child has a special circumstance surrounding, your school would be the best place to try and work out a compromise.