they may also be required to implement age verification
They are already required. Australia is requiring them to do exactly that. It's a safe bet that this will be ignored for now, at least outside of Australia.
Suppose the fediverse wanted to comply, what do you think the volunteers running it would have to do?
Well. Step 1 is monitoring legal requirements around the world. In all the 50 US states, 200 countries, and whatever other kind of jurisdiction feels important.
You have to age gate social media for 16+ in Australia. Some content is criminal in some countries. Some content is 18+ in some countries but not in others. Some countries require such content to be age gated, others do not.
What kind of age verification is acceptable also varies...
You need to constantly have your eye on new laws, legal precedents, or decision by regulators and adapt.
And that doesn't even begin to address the technological problems.