There are three sizes in this pattern, as shown in the photos, small, medium, and large.
However, this pattern is for amigurumi dolls/plushies, and as such they’re fairly small, even the ‘large’.
You can increase the hook and yarn size though to create a larger/smaller hat as desired.

The pattern is written in US terms, and has abbreviations like;
sc, sc-dec, sc-inc, slst, and front/back loop only instructions. Even with that, I’d say it’s a easy level pattern.

Have fun customizing your own versions!