The irony here is that on most things DeSantis is a complete asshat, but on this he's 100% right.
Social media is a dopamine hit machine and like any dopamine hit machine given to teenagers between the ages of 11-6, addiction is an almost inevitable result. This is why people become addicted to social media, video games, cigarettes and alcohol. A dopamine hit loop established at the right age is the key to creating a lifetime customer - something the cigarette companies have known for decades (yes, they really were marketing to adolescents all this time).
The negative effects of social media on the life skills and self-image of teenagers is just starting to become evident. The full impact probably won't be accepted by the average Joe for a decade or two, but the writing is on the wall for anyone paying attention.
The logistics of enforcing this are a technical problem and one that is amenable to solutions. Yes, you can't stop everything, but just because a solution isn't perfect doesn't mean it shouldn't be implemented. If you can hit 80% of the problem, that's good enough.