A more sensible approach to this law would be to require adult sites to include a clear marker in either an HTTP header or an HTML meta tag. For example:
This would allow locally run browser content blockers to automatically detect such sites without blocking them individually, and it would be trivial for site operators to implement. Since it would be mandated by law, sites that refuse to comply could be subject to legal action.
Of course, this would still rely on parents taking the basic step of setting up a content blocker before allowing their children unrestricted internet access.
<meta name="OnlineSafetyAct:SiteClassification" content="adult;nudity">
This would allow locally run browser content blockers to automatically detect such sites without blocking them individually, and it would be trivial for site operators to implement. Since it would be mandated by law, sites that refuse to comply could be subject to legal action.
Of course, this would still rely on parents taking the basic step of setting up a content blocker before allowing their children unrestricted internet access.