The finished circumference of this hat will seem very small. However, remember that these measurements are with the hat completely relaxed. The pattern isn’t knit overly tightly and it is based over ribbing which will allow for a decent amount of stretch. If you’re not convinced then altering the pattern is very easy. The base repeat begins with a multiple of 10 stitches. Cast on an additional 10 stitches (or as many repeats as you would like) and change all the number of times instructions to reflect the amount of 10-st (and then 11-st after rnd 9) repeats that you have.
Remember that adding additional repeats will use more yarn!

Hat shown measures 14” relaxed circumference and used
57 grams (approx. 103 ytards)