Writing large characters is more difficult in calligraphy. It depends on how big you want to write. The larger the characters are over 15 cm, the more difficult it is to write.
The strokes of large characters should be plump and vigorous, so they should not be written as thin as wood. The structure should be open and compact. You should practice large characters more often. After you finish writing, hang them up so that you can recognize them when you look at them from a distance. Writing mistakes will help improve next time. In short, writing large characters is definitely not a day's work. It requires foresight of the completed work, more practice, more thinking, and more creation.