I agree with the sentiment behind this law. Protecting children from accessing explicit and, more often than not, very disturbing porn, is a noble goal. However, I believe that this particular approach is flawed and unlikely to achieve its intended objectives.
First, verifying users' ages risks exposing their privacy. Doubt it very much that many people will be happy to submit their personal data to dodgy porn sites. Would you be confident that they have robust data protection systems in place? So many issues to think about, identity theft, harassment, etc. if any of the private info gets leaked. Also, where are the porn serves located? Which country? What regulations are the in place to protect users' data?
Then we have the issue of some determined individuals (including young people who tend to be more IT savvy) who will find ways to circumvent age verification systems, such as using VPNs or other anonymization tools. What is likely to happen is that this law will drive some users to seek out alternative, unregulated sources of adult content, which could be even more harmful.
As I said earlier, noble sentiment but a difficult one to implement successfully.