The standard for automatic grinders is around 15, while manual grinders usually have a little less (6-9).
As an aficionado making coffee at home, you’re not likely to need any more than 9 settings, though, one for each: three fine settings, three medium and three coarse. Of course, the more the merrier, but you only really need them for professional quality and if you are brewing across multiple methods.
Some professional grinders have over 100 different settings.