Depends on the film, and I believe the same can be said for a lot of places (just my opinion).

Like, you're bound to have Hollywood films more representative of life in America, however it will of course have some theatrics added.

There is also the elephant in the room: how bloody massive the US is. I've travelled through a bit, stepped foot in 39 States (if I'm honest I travelled around only about 25-28 or so), and it was easy to see a good variation in the way people talk, not just the differences in slang.

In a lot of cases the representation of a character would be based on the influence of a real person, however the amount to which the impression is exaggerated depends on the film or show.

I would not say my friends and family remind me of any film to a great degree, yet there will be some aspects within. However the same can be said about here in the UK.
We all know a bit of a Rodney, etc.

But in my experience I'd say no, I've rarely met someone who genuinely behaved fully like a TV or movie character whilst visiting and living there, unless they were trying to make an impression of the characters.

Hope this made sense.