For example, as we often say, "Calligraphy and painting are of the same origin", China's calligraphy is closely related to Chinese painting. They are intertwined in the long history, all using the brush as a tool and sharing some common brushwork.
For example, the composition of calligraphy works and the layout of seal cutting have a certain relationship with the design direction to some extent, and calligraphers with a strong sense of design are more likely to write wonderful works. This is just the most basic thing to learn as a professional student. If you want to go on this road, you need to read a lot of books, not just books on calligraphy.
Calligraphy is closely related to literature, history and philosophy. Without the support of knowledge, you may be engaged in calligraphy all your life and just be a writer. To give the simplest example, at present, all calligraphy and seal cutting exhibitions at or above the provincial level have set up text reading and peer review links, in order to prevent those contributors who can only write but have poor literary literacy from being selected. They simply copy some ancient poems or chapters of literary works, but they don't pay attention to whether there are complicated and simple words or other improper words.