Flat-knit Socks for Dolls - any size
This pattern includes sizing instructions for any doll (I think - it’s been tried for dolls with feet varying in length from 3/4” to 3”). It allows you to knit socks without worrying about knitting something tiny in the round. It has complete instructions for assembling the socks as well as examples in three different size / gauge combinations. I doubt that you will want to use yarn greater than about sport weight, but it’s up to you.