That depends on what kind of law you view this as. As a parental control like the V-chip (but hopefully with a higher percent of parents using it) it's nothing new.
It's not new but that was a dumb and irrelevant technology too. And didn't last for that reason (easily bypassed, not working with modern tech). Just like the clipper chip that was supposed to spy on us.
Not just "could be used in one", but age verification is the raison d'être for the introduction and existence of these fields. Not sure why some people pretend otherwise when it is obvious.
Do you think parental controls requirements are generally a fraud, or if it's just this law what makes it special?
I don't think the California law makes it easier in any meaningful way to pass age verification laws, considering how many age verification laws have already passed. I see it as something that has real uses by itself and also can get many apps/sites that would have done US-wide age verification to trust the setting instead.