Lecter

There are widespread beliefs that exposure to pornography hurts teenagers, and as a result they are sheltered from any explicit materials. I've always said that it creates grounds for grooming, because with the start of puberty most human beings begin to seek sexual gratification, and everyone who can offer porn holds power over the teen. But I'd step away with my claims if there was clear evidence of harm of porn, because the risk of grooming is better than direct damage (I'll elaborate on this point later). Yet nothing of the kind was confirmed.

"Reflecting concerns over adolescents’ use of online pornography, which include fears that immersion in pornographic imagery of impersonal sex and hypersexualized bodies may have negative consequences for young people’s psychological health, this study set out to assess temporal relationships between pornography use and various aspects of adolescent mental well-being. <...> We did not find consistent evidence that pornography use was associated with negative changes in subjective well-being, symptoms of depression and anxiety, or self-esteem in either gender."

(source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6088458/)

One important note I need to make, porn should not replace sex ed, children and teens should receive information about their reproductive health from medical sources, whether at school or individually. In case when it is provided, there will be no harm from porn. Therefore there's no logical reason to make NSFW materials 18+.