For more details, I recommend reading material from the advertising industry, starting with Edward Bernays https://en.wikipedia.org/wiki/Propaganda_(book)
"Most significantly, they found that the number of reported cases of child sex abuse dropped markedly immediately after the ban on sexually explicit materials was lifted in 1989. In both Denmark and Japan, the situation is similar: Child sex abuse was much lower than it was when availability of child pornography was restricted."
(I must admit I haven't looked into it much however, you will have to decide for yourself how much you trust Diamond M et al).
However, anecdotally, after I masturbate to pornography my desire to engage in real-life sexual activity markedly goes down. That is the point of masturbating to pornography, isn't it?
I'm sure there are places where porn has been illegal but later become legal, looking at how it changed the rape statistics might give some weak evidence (though correlation is not the same as causation of course).
Drinking coca cola isn't illegal or even looked down upon. Rape porn isn't advertisement for rape and is not meant to encourage people to rape. Coca cola advertisement/product placements is designed to make people buy it more.
The two cases are in my opinion very different.
Do you suggest rape porn or rape scenes in movies promote more rape in the real world? What about violence in video games? I don't claim to know the answer, but I've thought that was disproved (though I haven't really looked into it).