Excuse me, is there a specific method for calligraphy pen, which is not pure theory, and is there a practical answer?

When posting, start with regular script, such as Liu Kai or Yan Kai, and post with the original font size. Post slowly and experience the power of pen and paper. How to put the paper in, how to spread it out, how to move your wrist (watch your wrist, don't move) and how to raise your pen are all realized when you are near. Otherwise, no matter how good others say, it's not yours.