How should I confront my 10yr old nephew that porn and explicit content is bad at such young age??

Last week, in a family function, we all boys and my cousins' (male) son and friends, all were in the hall room (about 12 people). Don't remember but my nephew (11 M) started arguing with one of his cousin (12 M) and mentioned "MIA Khalifa." Atp, like me everyone I was just too shocked to react because it's a sensitive topic especially involving a kid and my cousin mingled with feeling of dismay and anger, slapped him and ask him to go into his room... And as soon he left the hall room crying, almost all of (boys) crept out of the room as well as it was very strange for us to make an eye contact with anyone after that point. And later, I checked my nephews' phone and didn't see any explicit searchs... But I've always felt that he knows about porn and explicit content.... And I was just wondering what will happen to these kids when they'll have their personal phone and move out of city for studies. And after that point, I haven't talked to him at all and avoiding him (as he lives in the home next to mine) and also I'm busy with my collage... But if I talked to him about this... How should I? I just want to make sure he didn't want him to become a 11yr porn addict? How should I address this situation without making a fuss about it?