First act (3 episodes) came out on Netflix today. 2nd act in a week, and last act a week after that
Alternate sources: Go to Yandex (dot) com and search "Arcane Season 2 stream online free". Yandex is a great resource in general for any free streaming, the first link always works perfect
It's amazing, just don't read opinions or discussions about it from people you don't trust because there's a lot of class conflict in the show. It's not like, revolutionary propaganda or anything btw, just a really aesthetic, emotional drama with a gripping plot and great characters