When our family all got bikes when i was a kid, we got three 26" wheel Raleigh three-speeds, and for my little brother, a 24" wheel Raleigh three-speed. So I googled '24" wheel Raleigh', and looking at the images, it appears that they've made many 24" wheel models over the years, with mountain, road, and hybrid/upright/comfort styles. Bikes from other manufacturers appeared as well, of course. Most did not seem to be obvious kiddie bikes.

I suggest looking for a 24" wheel Raleigh, or other make, without worrying about the labels 'kid', 'child', or 'youth' that they may be associated with.