If she has basic keyboarding skills, using the correct fingers on keys, I would just move into typing narrations, not really add a subject, just start using typing more. That is what we did. So my 7th grader does some written narration as well as typed narrations. My younger two are still mastering keyboarding so still in practice mode.
Or you could have her type poetry and then illustrate it or decorate it, combine typing and art.
I really think typing just needs practice to improve, so maybe even ask what she is interested in doing. Once skills are there I don’t think I would do typing as copy work, typing just to type, just work it into subjects that are already being used to keep up the practice.