Rockstar's open worlds have always handled bridges well. Vice City especially - it's built around them. The city itself is split between barrier islands and mainland, and the bridges connecting them are part of the city's actual geography.
We map the visible bridges here. See the Keys bridge route piece for the long-form bridge route.
The causeways
Visible in the trailer footage are at least two causeways connecting the art deco strip and the rest of the barrier island to mainland Vice City. Long, low stretches over placid water. Think of the real-world MacArthur or Venetian causeways - in style, if not in name.
Causeways are crawling with traffic in the trailer frames. It makes sense that they'd be choke points - the only way to drive from the strip to downtown is across water, and causeways are how you do that.
The Keys chain
There are numerous bridges connecting the islands south of Vice City. A few are short hops, while one or more are long spans across water, consistent with the real Seven Mile Bridge. Documented in depth on the Keys bridge route page.
Drawbridges and canal bridges
Vice City clearly has canals - covered on the canals page - and the canal frames suggest drawbridges. Drawbridges raise and lower in the real world; whether they do in GTA 6 hasn't been confirmed, but it would be in line with the overall attention to rendering detail we see in Trailer 2.
Highway interchanges
Trailer aerials capture where the coastal interstate meets surface roads at interchanges. Cloverleaf-style and stack-style interchanges can be seen. They aren't 'bridges' in the dramatic sense, but they are part of the overall structure.