My child is younger, so has started from the beginning of the series of writing courses, they've completed the first two, we would continue but in person schooling interferes at the moment:

The Process of Writing
Writing for an Audience
Crafting the Essay - https://cty.jhu.edu/online/courses/arts_humanities/crafting_the_essay.html
Writing Analysis and persuasion - https://cty.jhu.edu/online/courses/arts_humanities/writing_and_persuasion.html

The first two courses are designed such that there are around 4 actual projects across 10 lessons, you submit one, and while it is being marked you start the next project. Then in a latter lesson you start another pass over a previously marked work, and use new instructions and teacher feedback to refine the work. So feedback, how to use feedback, explicit teaching on revisioning, etc are the whole point of the course.

I was not impressed by the grammar course my child did. And the reading courses were fun but not super challenging. The writing course has been really excellent.