I think a high IQ at a young age is indicative of raw processing power. They can keep things like shapes and numbers in their head and manipulate them correctly

I think a high IQ at a young age is indicative of raw processing power. They can keep things like shapes and numbers in their head and manipulate them correctly to pass the kind of spatial and mathematical questions you'll find on an IQ test. It won't tell you much about motivation and grit, though a 6 year old focusing on a test and trying to get it right gives you hints as well. Of course, from there, parenting, education, and especially the intrinsic processes of the individual themself will all influence what is done with that raw ability.