There was a lot more variation in clothing early in the series. We used to see jumpsuits, anti-radiation suits, pocket-covered "load-bearing vests," special clothing for medical personnel, and so on and so on.
By the end of the third season, they were down to only the basic tunics for pretty much everybody, though. I suspect that this was a cost-management measure, but it's a shame. I really liked the variety of uniforms seen in early episodes.
Now, for civilian clothing, well.. in TOS we saw very little of that, and it was generally lacy frilly things for girls, or very basic "jumpsuits" for men. I suspect that''s part of why they went so overboard in TSFS with the various civilian styles (and I feel for Walter Koenig for having to wear the "Buster Brown collar" to this day!)