Hi @Greystone0
It seems all you can do in the present version of the host dashboard, is set the number of guests and extra guest fee. There is no longer a place to specify minimum ages, and I've never seen a way to program the mix of adults and children (although you could somehow try to address this in the house rules?).
Here's an Airbnb family policy link:
https://www.airbnb.co.za/help/article/433