Those three games are the best, most impressive, and most fun the Switch has to offer. If you're in to multiplayer, add Super Smash Bros (it's not really my thing, but it's highly praised and beloved, some might swap Smash Bros for Mario Kart in my list). If your kid is into Pokemon, get Pokemon Sword/Shield and Pokemon Let's Go Pikachu/Eevee (Sword and Shield are the newest installations while Let's Go Pikachu/Eevee are remakes of the original games with a Let's Go Pokemon twist).

The Switch has tons of other games that are great, but those three are the essentials.