Atorrante is an interesting slang term, particularly common in some Latin American countries like Argentina, that translates to 'bum', 'scoundrel', or 'good-for-nothing'. It's a colorful and somewhat provocative word.
In the song, Big Soto says, "Y yo no quería sonar atorrante" (And I didn't want to sound like a scoundrel). He uses it to acknowledge a certain swagger or boastfulness in his lyrics, suggesting he's aware his success might come across as arrogant, but he's just stating facts about his achievements.
Big Soto opens by naming the rule he is about to break: "Aquí la escuela es ser callado, morir discreto" (Here the lesson is to be quiet, to die discreetly). Then he spends the rest of the song doing the opposite. He counts what he has and what he is still waiting on: "Aún no tengo un Patek pero brilla mi Phillie" (I still don't have a Patek but my Phillie shines). There is gold at his neck, champagne at LIV, and a steering wheel you have never touched. Then the hook lands, one line after the flex: "Y yo no quería sonar atorrante" (And I didn't want to sound like a show-off). He knows exactly how he sounds.
The second half opens a door: "Bienvenidos al mundo de Sotorius" (Welcome to the world of Sotorius), and the world turns out to be a Venezuelan childhood. Codeine goes into Frescolita, the cream soda every kid there grew up on, and he prefers it that way: "La prefiero así porque sabe más dulcita" (I prefer it like that because it tastes sweeter). After that it is all cartoons. Timmy has a godfather and Soto doesn't, the green he is burning is not Cosmo, the high leaves him "en Nickelodeon" (on Nickelodeon), and by the last bars he is Ichigo holding the sword. The brands are new. The reference shelf is the one he had at ten.