Annoying that it says “one size”, but not what size that is!
Did you check your gauge? At the stated gauge, it should be 92cm or 36", which is a pretty small size. There’s very little shaping–you could cast on enough to fit yourself in a multiple of 4 stitches and forge ahead. You’d have to adjust the row count for the armholes and the stitch count around the neck. However, you could run out of yarn if there’s a large size difference
Probably possible to adapt, but maybe a bit much for your first garment? Try looking for other patterns that call for 8mm needles? If nothing else, they’d tell you if you have enough yarn for your size and/or how much more you’d need.
I didn’t even notice at first that the ribbing is cabled…the mix of yarn kind of obscures the stitches.