There's not a big book in a vault at CBS containing secrets unknown to the general public, no. We rely on the same references materials everyone else has: the official guides and encyclopedias, websites, and, most of all, the original episodes and movies. The latter are the only final authorities.
The one exception: sometimes, back in the day, if we had to start writing the novels before the latest spin-off hit the air, we might be provided with an early "bible" for DS9 or VOYAGER. But these documents tended to be only about fifteen pages long, just enough to introduce the basic concepts and characters, and we're quickly superseded by the actual shows once the series were up and running.
The original "bible" for VOYAGER, as I recall, called the EMH "Doc Zimmerman" and described Tuvok as an elderly Vulcan who acted as a mentor to B'Elanna. Obviously, that bible was not infallible.
And the DS9 bible just introduced the set-up and a basic diagram of the station. There was nothing in it about the Founders or the Dominion or any of that. As far as I know, that was all invented later.