Ours learnt on Early Riders from before they were two (without brakes), then skipped on to Islabikes Knoc 14 when they were 30mths. As most children learn quicker than adults, they learnt after a couple of minor spills that pulling the little lever on the handlebars slows them down. Even better if they pull the little one on the left first, cos that means cool skids!
Doesn’t stop them riding into trees now and again, but they learn and adapt ie don’t worry about it.
ps. Ours still ride their balance bikes, and either drag their feet on the ground to slow down, or wedge their feet on to the tyre. tbh our balance bikes look absolutely battered now!