I wouldn't recommend any birds for a child at all.
They are not easy to look after if you want to do it right - a parrot can't just live off of sunflower seeds and have a mirror and one or two dowel perches in a small cage.
They are extremely smart and need tons of enrichment and stimulation. Along with a variety of healthy foods - cooked veggies, fresh fruits and veggies, parrot pellets, and 10% of their diet should consist of healthy seed mixes. Vets for exotic pets are expensive, and you need an Avian vet for that - normal vets aren't specialized to treat birds.
They also don't do well alone as they are flock animals, so if they are alone, then they need even more out-of-cage time and time with their human. Long lifespans as well. Cockatiels can live up to 25-30 years. That's a long commitment.
Birds, and Cockatiels especially are amazing, but not for kids.
Source: I have several parrots ranging from Budgies to Cockatoos, do work for a veterinarian, and am one of the Cheeky Beaks Parrot Rescue team members.
I handle the surrender cases of neglected birds that are either abused or given up for various reasons - including young children that lose interest in the bird - I'm not saying that's going to happen with your child, but it's one of the main reasons that birds get sold or are surrendered to us).
Parrots are the third most popular pet - after dogs and cats, yet they are the most neglected, surrendered or given away.