Charcoal is both a fun but very difficult medium to work with. I do these traditionally with an extremely small mixture of my B6-B8 Graphite pencils. I also work in charcoal digitally using Krita and customized Charcoal brushes. The piece on the left was done in Krita.
Prices for these types of pieces, especially those with more detail, go higher than my pencil art.
The maximum size I can go with Traditional Charcoal is currently 2ft by 2ft and a half. Larger canvas would need to be discussed in detail.