Just how are you helping your readers by taking heading levels up to 11? John McGhie, MVP and guru for all things numbering-related, firmly suggests – as far as I remember; can't find the reference immediately – you should stop and think once you get past four …

When headings re-appear in the ToC, they are displayed using the ToC styles. Generate your ToC, find a level {whatever} entry and update its ToC style to give the visual results you want.