Is 2016 Winnebago Journey prewired for brake controller?

Brake wiring using the typical electric brake controller under the dash always uses a blue wire going back to the trailer hitch to connect to the towed vehicle. If you see a stray blue wire under your dash, or back at the hitch, then it's probably wired for it. It's always best to check the diagrams for your model of course.

Here's a pretty neat trailer wiring diagram covering all the standard connectors that might be back near the hitch: Trailer Wiring