I’m a little confused by the wattpadders showing up to AO3 all aghast at the existence of “RPF, Underage, Trafficking” tags like my dude what did you think your ‘my evil stepmom sold me off to one direction’ fic was? That is how that fic would be tagged.
AO3 is an archive, wattpad users. It's not a social media site and it doesn't have an ingrained algorithm. You will not get famous. Your fics will not be recommended automatically by the system. You post your fics for the love of the game, that's it.