There’s a maximum of nine levels available in Word multi-level numbering. That’s enough for the seven dwarves plus two more. There’s a way to get more than nine levels.
A Multilevel list setup shows 9 levels.
Need more? Perhaps create a separate multilevel list with custom numbering starting at 10?
It might be better to restructure the document because lots of levels can become unwieldly.
Debugging a Word list problem
Faster Numbered and Multi-Level Level changes
Word multi-level lists, new list, reset numbering and more
