No, there isn't. Almost all porn that is accessible to children is on freely available social media like instagram and twitter. Not on Pornhub.
Twitter and Instagram, then, are not businesses that make money selling content to viewers in an indirect manner where the viewer provides eyeballs to an advertiser who then provides money to the platform, right?
Are you saying kids don't go to pornhub?
No I'm not.
Children don't exactly have a lot of money, especially in a form they can spend online. Porn companies want customers who can actually afford to buy their products!