I think the pattern KK used for her hat and booties ensemble (in the blue self-striping KP sock yarn) has sizing in it for older children and adults too.
I seem to remember printing out that pattern to use for my 18 year old (and 6'2" tall) DS since it had so many sizes.
If I'm mistaken, then I'm having a :doh: :?? moment.
Hope you find it.
Happy Knitting :XX: :XX: