Do you have to learn Composition Theory and Harmony to compose?

The basic four disciplines of composition theory are harmony, polyphony, orchestration and composition, and they must all be learned. Self-taught professional knowledge is definitely not solid enough, and if you don't believe me, you'll let him write a symphony out to try, and he'll be 100% unable to write it. Of course, if you just engage in pop music, you can listen to it more and write it, it's not that difficult. If you don't do jazz, like Jay Chou, it's not hard to write. The real NB ones are the ones who play jazz and improvise, just being able to write songs is not a skill.