Australia's been down this road before with the failed 2019 age verification bill and the Online Safety Act. The technical implementation challenges are enormous - from VPN circumvention to privacy risks of ID verification systems.
Well the age assurance is only for logged-in users, so they can just log out.
The article doesn't quite spell it out but I assume you won't be able to turn off safe search unless you log in with a verified 18+ account.
This is how Youtube works now. Age restricted videos can't be viewed without logging in.