When I was little, my great-grandmother crocheted me a pair of tube socks. They weren't very comfortable, being bulky acrylic, but I loved them and wore them from before I can remember until high school.
I found a better way - these are spiral socks. They are STRETCHY. And I used the STR to make a pair for the kiddo. Lest you doubt their ultimate stretchitude...
On the just-turned-four-year-old:
On my size 10 feet: