Two observations here. One on the legislation itself and one on the impacts.
Firstly, not everything that claims to be protecting the children is being pushed for that purpose and our politicians may not even know the real reasons. Reportedly (I have not verified) in the USA some age verification legislation is being pushed by groups funded largely by Meta (Facebook). One reason suggested is that they have a massive exposure to fines in the US via COPPA and age verification could offer them protection. Ofcourse another reason might be that the tech industry is substantially funded by harvesting people's information, habits and connections for various nefarious and profitable purposes and age verification can be a new source of information about people. There are companies like Palantir especially that will be attempting to mine as much of that information as possible. The eSafety commissioner's previous employment and associations make her appear less independent that I would like. I also don't believe most politicians really know who has been pushing for these changes.
Secondly, not all adult sexual content online is the same. The "free" sites are funded by promoting paid sites and advertising. They had no age barriers. The assumption always was that these well known sites would be blocked by responsible adults using simple filtering software. They will now require verification for visitors from locations where that is mandated. The paid sites already have a form of verification via payments and likely nothing will change substantially. All the kids today, as they did decades ago, likely have a sad friend with a massive porn stash who happily shares it for social credit. So essentially the Internet is getting a partial reset to the late 90s before everything good got commercialized and a bunch of psychos got stinking rich and started fucking with democracy. Bring on the P2P.
Don't age verify. Find another hobby.
My kids have used Linux from birth. One of them is voting age now. A Chromebook is Linux. They mostly just open steam.