This sweater is worked in stripes until the very end. The grid effect will be added by crocheting over the purl stitches with the contrasting color.
The inspiration comes from the Rodarte grid sweater from the SS2014 collection.
I adapted the motif to an “age-appropriate” shape for an effortless, yet chic look.

video tutorial on the link for finishing the neckline with the Kitchener Stitch.