1A seems to mean it can't simply be banned, and frankly, if it were that would just create a black market for it.

Better to make it tightly controlled.

Outlaw all non-subscriber porn services on the internet. As part of registering as a subscriber a person should have to register their identity with the .gov. This prevents children from just hopping on to pornhub or similar sites.

The .gov porn consumer registration acts as an access pass for all internet porn and provides an identity for billing. Furthermore it allows tracking of porn consumption through mainstream channels. The tracking alone will discourage porn usage.

Pass a law banning the depiction of illegal acts in pornography. Depictions of drug usage, incest, rape, and other illegal acts are forbidden. This kills entire genres of pornography.

If porn must exist, regulate its usage into something shameful and regulate its content so that the very worst of it is illegal and thus difficult to obtain, and make it unavailable to people below the age of adulthood.