"Rang" is a principle of calligraphy. Also known as "welcome". That is, all local structures (stippling, radicals, etc. In short, it should be friendly and give and take, which is the harmonious unity of the whole. A word is an organic whole. In this whole, some components occupy the main position, so nature occupies more space. Then, other parts should shrink accordingly, showing a gesture of welcoming the main part. In short, there must be welcome, and if the parts don't give way to each other, the words can't be harmonious and organically unified, and the words become a mechanical patchwork of the parts, which is not vivid and beautiful.
The principles of welcome and surrender also apply to the layout of calligraphy. There is also the problem of mutual welcome and submission between the parts that make up a calligraphy work (especially cursive script). If handled well, all parts of the whole picture will form a living organic whole with artistic beauty.