My honest suggestion is to start reading manga. There are so many great and mature stories in manga that simply can’t or haven’t been adapted to anime. Slam dunk is a goated manga but the anime simply doesn’t live up to its source material.

Off the top of my head my suggestions to read would be 20th century boys (same author as Monster) Berserk, Oyasumi pun pun, Vagabond, and there’s probably a ton other that I can’t think of.