The child is only nine years old, as long as the handwriting is clear and the strokes are straight. There is no need to rush him to write such beautiful words. The so-called crash copybooks on the market are not designed for children.
As a child of this age, the first requirement is to write correctly and standardize. You can't ask him by adult standards. Poor handwriting is mainly due to lack of interest in writing, but homework has to be done and can only be perfunctory. In this case, it is useless for you to force him to practice writing, but it will make him more disgusted with writing.