Depends on the law. Some of them say that the age range must be provided to all applications through an API, and all apps and “app stores” must filter content based on this value. Others say that this isn’t enough and you actually have to verify the age based on some commercial scheme like CC or ID verification. Some say you have to send the age to websites. Many of these laws seem to be in direct conflict about what is allowed and not allowed.

In all cases, at least in the US, these laws violate the first amendment (as code is a form of speech), and freedom respecting users and devs need to resist them until they can be defeated in court.