allow app store access but no purchases

My understanding is that iOS parental controls let you (a) disallow in-app purchases, and/or (b) hide the app store altogether. I am hoping for an option where the child can browse the app store and download ("Get") free apps, but not be able to download/buy apps that cost money. Am I missing something, or is that not possible? And if not, why doesn't Apple offer that? I want my kid to be able to, say, hear about a new game from their friend, download ("Get") it for free, and play it without me having to be involved. But I don't want them to be able to buy an app or make in-app purchases.