As you said, the size of the words changes, that is the feeling of the overall composition, and the whole article looks very coherent. In fact, writing and copying are different, just like the song style in a book, the size is exactly the same, and there is no aesthetic feeling when you paste it. When an article is written down and has a size, it looks good when it is put up.
Without strength and momentum, who made perfection. If you write too much, your lines will naturally be solid.
It is suggested not to print copybooks, but to write according to copybooks, and analyze word by word, instead of pursuing speed.
hope this helps