Don't just reward your child for being smart.

Reward them for listening, integrating, being nice towards others, relaxed, comfortable, flourishing, in their lane

Praise the effort not the result. And especially don't make it into identity of the child.

Best: good job studying for that exam.

Meh: good job passing that exam.

Worst: you so smart, everything comes easy to you.

The answer here is actually teach them to self-evaluate, e.g. What do you think about your drawing? Should we hang it up?

Got this from Steve Peters: https://en.m.wikipedia.org/wiki/Steve_Peters_(psychiatrist)