When you start Animal Crossing: New Horizons there are 8 Hairstyles that you will be able to choose from when creating your very own Villager. However, there are more Hairstyles that you can unlock as you progress in the game.
You can “change up your look” at any time using a Mirror or Vanity, although you will need to learn the DIY recipes for these items to craft them or hold out hope that such items rotate into stock at Resident Services or Nook’s Cranny.
Mirror or Vanity secured, to maximise your Hairstyle (and Hair Color) options you will need to save up enough Nook Miles to redeem on the Nook Stop multimedia terminal in Resident Services to unlock three customisation packs: Top 8 Cool Hairstyles (2,400 Nook Miles), Top 8 Pop Hairstyles (2,400 Nook Miles) and Top 8 Stylish Hair Colors (3,000 Nook Miles).
That’ means that you will need 7,800 Nook Miles to unlock all three of them, which will allow you to choose from 24 Hairstyles and 16 Hair Colors.