Apparently it used to be. However Mr Trump lost it in 2016 but won the state anyway,so it’s not such a good bellwether anymore.
I’ve actually heard St Lucie is a bellwether, maybe as well as Pinellas. Not sure about that though.
On another note, the best county bellwether is Vigo County, Indiana, and they have been right since 1888. Last week they had a huge truck rally for Trump. You never hear publicly how their polls are shaking out. They make me optimistic.