How to write big art font?

The problem is a bit vague, I don't know how big it is, and there are many kinds of calligraphy. I don't know what kind of calligraphy you are talking about. I'll try to answer:

Large-scale art characters generally use bold characters, such as writing propaganda slogans on the wall, with vertical rectangles as the best, laying spaces and text boxes with chalk, and drawing with chalk close to the background color as the best. Then write the stroke structure to be written in the text box with chalk single line, and then use a blackboard brush (as wide as the stroke width of the character) to pick up paint or propaganda fuel to write. For example, this set of characters is bold.