Question I’m curious about to all realistic fiction writers

How realistic do you make your stories? By that I mean if the story is set in modern day or some time in the past, how far do you go? Do you include big events from that time, learn the slang your character would realistically use in that time period and their age, do you research how communities and people act, use real life products from the time or new current technology, all that. Just a small question that’s been nagging at me.