the whole plotline of the 800+ eps & ongoing series is: he's trying to expose a bad org who made him a shota by accident (their poison was meant to kill him) because he's a detective dedicated to exposing crime.
I suppose adult Conan (Shinichi) is still pre-18, though
[spoiler:lit]wish I could take me some APTX4689[/spoiler:lit]
fun sidenote: his anime is so popular in Japan, its movie of that year beat avengers: end game, one of the very few countries to not have end game as no.1. detective conan is a japanese household name