Netflix series spoke?

Is English spoken in series such as riverdale or American English? General series

Most of the series are produced in America, i.e. American English.

It depends on several factors:

Country of production: Series made in the US or by US companies typically use American English. BBC productions, on the other hand, tend to be British English.
Characters: If a series character is British, he will mostly speak British English. There are differences whether a British actor has actually been cast or someone else is trying to imitate it. Conversely, of course
Place of action: e.g. Doctor Who episodes that play in the United States have British leading actors, but just to create atmosphere the others speak American English. The other way around, of course.
Target audience: Series for the American market generally use American English.

Since most series are shot and produced in the United States, series that use American English are often (at least at least) for American audiences.

In addition, of course, English has more dialects than just these two. Australians or New Zealanders are sometimes also there, as well as Scots and Irish. Broadchurch, for example, is difficult to understand in parts, since David Tennant and his colleagues speak wonderful Scottish dialect. And American English also has dialects and slang. Texan dialect is often heard in series, for example.