This is a plain, toe up crochet sock, that can be customized to fit. The instructions are for a size 9/9.5 American, but the size can be adjusted simply by making the foot and cuff lengths longer or shorter. In general, the foot length should be about 2 inches shorter than your shoe size - in my example, the foot length is about 7 inches, because I wear about a size 9 shoe.

I have used elements from various sock patterns to create this one that works for me - I’m creating crochet socks primarily to wear in the home to keep my feet warm, not necessarily to wear inside shoes. You can make these thin enough to wear in shoes, using a thinner yarn and a smaller hook, but you would have to adjust stitch numbers for the toe and heel to accommodate the change.

I’ve made these as large as men’s size 12, and down to a child’s size - you just need to adjust the math.