Read books, read newspapers, chat on the land-line phone for hours.
Before the cliché of everyone being with their faces in smartphones there were clichés about husbands who do nothing but read newspapers all day, or teenage daughters that massively inflate the phone bill because she's talking with her friends for hours, or children with square eyes watching brain rotting cartoons all day.
Playing outside a lot more, which was really fun. Hit the beach or swim docks and jumped off the highdives. Went camping. Bike adventures, etc. Lots more physical toys like nerf, Lego, beyblades, etc. CD music players, cassette music players, or MP3 music players, depending on the era.
People on the metro buses would read the paper to pass the time, listen to music, or read a book.
Back then, you could rent videos or games at a rental place, and there were many more physical hobby shops (there still are, but for live stuff, like aquariums now). Malls were a lot more alive and were true third places. Though even back then, I found people gorging themselves in a materialistic frenzy rather...distasteful. People still do it, just via Amazon and fast fashion online.
The biggest things I remember were how chill people were, the ubiquity of newspapers, smoking and cigarette holders outside, a lack of really any graffiti, and people being incredibly chill and a bit more open. There were also like, zero bike lanes or rail, so everyone drove everywhere.
Usually I use my phone when I an sitting around waiting for something. In those times, before I had a phone, I would always think about things I could and should make, and the techniques and mechanics of how they would work.
I read a bunch, and played a lot of video games. I am on the older-end of Gen z, so smartphones only became a thing when I was older, so most of my childhood was spent on computers running a mix of windows 98, Windows XP, and eventually Linux, where I got most of my books and almost all my games.
You ever stand behind a couple of geezers in line somewhere and they start talking about some random stuff? They didn’t know each other. They were just bored.