A large part of any science fiction author’s job is creating a world, far from a chore this is a large part of the appeal of science fiction.
The great secret of course being that we can’t really create whole worlds, creating everything a whole world holds would be the work of thousands. However like all artists you can cheat.
You create enough details to make people think the world is full and whole. There are any number of large and important things that effect the whole society, however you also need the small things.
The first is entertainment. This is not just what people do for fun but what media do they use? Do they do full VR, holodecks, books, TV ect. Also how much do they cost? Do rich people have access to holodecks, while the poor have to settle for books and movies and the middle class has VR?
And of course if they are anything like us they are going to have some taboos. How would people feel about a VR where strangers can having sex with them?
And of course don’t neglect to think about shows or VR’s or whatever people talk about over the fusion cooled water cooler.
Next of course is what people dislike about the government and how things work. There will always be people who have a problem with the government. Make sure to distinguish between grumbling and real rebelling, you don’t want someone who just started your book to think the character is a revolutionary because he is grumbling about the 2% tax hike.
Sayings and swearing are next. Both sayings and what swears people use do shift over time, not as much as you might think but they do change. If your writing a book set in fifty years you might not really need to change anything, but if its set in five hundred? Yes you should change them, even if just a little, just enough to show the difference.
Where do people meet? By this I mean where do they congregate, after all things like shopping, working and maybe even being taught could be done from home. So think about how people would meet, you may have a lot of social clubs that exist solely to get people out and let them mingle for example.