Where to get event cosmetics?

Hi, I'm a new player, was looking at the beauty guide and liked a lot of the hair /faces that were marked as "Event" cosmetics.

my question is how do we get these? Can you only obtain them during the events, like the 2019 event cosmetics etc are just gone now, and there's no way to get those cosmetics anymore? When are the events? And where do we go to get the cosmetics if/when the events are active? Just regular plastic surgery/barber shops or are there special locations?

Sorry for the noob question I couldn't find any information about this through a google search.

Thanks!!