I've lived in many places in the USA, from SF to Chicago to NYC to Utah. And honestly, they're just not all that different.
People's sterotypes of the predominant LDS (Mormon) religion make them believe that Utah is unique and a theocracy.
In reality much of American law is based on very similar Christian moral standards. Most states are majority Christian, the laws reflect that. The difference in Utah is that it's mostly _one_ religion, rather than say a mix of various protestant and Catholic faiths.
Try walking around fully naked in any of the places I mentioned above, like into an office building or a university or other establishment, and I guarantee you that those more liberal places will also not tolerate that behavior. Not due to any direct harm you'd be causing, but due to moral standards encoded into culture and law.
Same with alcohol, tobacco, and all the other "vices" people believe are banned in Utah (they're not). If you drive around downtown Salt Lake City, you'll see bars, signs for cannabis cards, smoke shops, and even a some decent breweries. It feels a lot like most American cities. (Granted that elsewhere in Utah like in Provo, you see many fewer of these). Nearly every state allows, but restricts and limits all of these substances and activities in various ways, from licensing to age limits, and Utah is not really very different.
For porn specifically, there have been laws on the books in many states to restrict access to minors for a long time. In the age of magazines, do you think it was legal for a business in California to sell such materials to a minor? If not, why not? Because it was either deemed harmful or immoral, beliefs eventually rooted in religion.
Beyond that, is Utah actually different than other places most Americans would respect for being more "level-headed", like the UK (https://www.wired.co.uk/article/uk-porn-ban-digital-economy-...) or Germany (https://www.wired.co.uk/article/germany-porn-laws-age-checks)?
Now, this specific law is impractical, Utah simply does not have the market power to induce a player like Apple or Google to make device-level age verification the way that Pornhub is suggesting. So the state of Utah has put into effect a law that will result in reduced access to porn (followed by subversion through VPNs) rather than actually age verification. And in the process the state is hurting its reputation.
But the generalizations here about the state due to religious and political biases are just not helpful.