Part of getting the bike right for kids is getting the cranks the right length and the gearing right as well. It’s more than the frame size.
But if it’s spec’d right, has good hydraulic brakes, shifters, and wheels it will be a real enjoyable ride and you’ll have a biker for life.
At 9 years old, you may consider a 26” wheel set on an extra small frame depending on the kids height. 24” can get real small real quick at that age.
The bike listed in the subject line is awesome but is a little higher than your price range. If you’re interested sign up to be notified when it’s back in stock. They’re usually listed as out of stock but get more frequently.