Do I have to hire a teacher to learn calligraphy?

If we want to improve hard pen calligraphy, we don't just want to write well, then we'd better find a teacher to guide us. Calligraphy can be said to have a wide range of contents, extensive and profound. It is not enough to study by ourselves. We need to find a teacher to teach us from the standard posture of writing, the influence of writing height on the size of words, the structure, brushwork and layout of words.