Rockstar's open worlds have always done bridges well. Vice City in particular is built around them - the city is split between barrier islands and mainland, and the bridges that connect them are part of the city's geography.
We map the visible bridges here. For the long-form bridge route, see the Keys bridge route piece.
The causeways
At least two causeways visible in trailer footage, linking the art deco strip and the rest of the barrier island to mainland Vice City. Long, low spans across calm water. A real-world MacArthur or Venetian-style causeway, in style if not in name.
Causeways are dense with traffic in trailer frames. They're plausibly choke points - the only way to drive from the strip to downtown is to cross water, and the causeways are how.
The Keys chain
Multiple bridges link the islands south of Vice City. Some are short hops; one or more are long water spans, consistent with the real Seven Mile Bridge. Covered in detail on the Keys bridge route page.
Drawbridges and canal bridges
Vice City visibly has canals - covered on the canals page - and the canal frames suggest drawbridges. Drawbridges open and close in real life; whether they do in GTA 6 is unconfirmed but consistent with the general rendering effort visible in trailer 2.
Highway interchanges
Trailer aerials show interchanges where the coastal interstate meets surface roads. Cloverleaf-style and stack-style interchanges are visible. They're not 'bridges' in the dramatic sense but they are part of the overall structure.