Generally speaking, calligraphy works are all traditional Chinese characters, especially brush calligraphy. China's calligraphy has a long history. In ancient times, traditional Chinese characters were commonly used, while simplified Chinese characters became popular only after the founding of New China. If we want to learn calligraphy, we must persist in it, and we must learn ancient times in order to get its essence. After all, traditional Chinese characters have richer connotations than simplified Chinese characters.
But now more and more people use simplified Chinese characters in their calligraphy works, and hard pen calligraphy is the most common.
Can simplified characters be used in calligraphy works? Nothing more than personal preference! The most important thing is to unify complexity and simplification. Calligraphy works with simplified characters cannot have traditional characters, and calligraphy works with traditional characters cannot have simplified characters, otherwise it will be ridiculous!