Real Florida has noticeable tide variation. Whether the GTA 6 map has dynamic tide is a real question. We hedge.
Why it might exist
Storm imagery in trailer 2 shows water level changing. That implies dynamic water-level systems exist somewhere in the engine. Whether they extend to a real tide cycle is a different question.
If tide existed, it would change traversal at canal-side, marina-side and Keys-side locations during the cycle.