The size the pattern is written for will fit most people,
If you want a larger size use 4 mm needles instead of 3.5 mm and 4.5 mm needles instead of 4 mm, or just use thicker yarn, or both
Similarly if you want a smaller size you can either use smaller needles in a similar fashion as above (3mm vs the 3.5mm, and 3.5 vs the 4mm) or you can use thinner yarn, or both.

I hope you enjoy the pattern!
It has a very warm feel, especially in windy winter days, but is also suitable for any autumn or spring time without being too warm!

Happy Knitting!!!