want a big tree FAST??? Sycamore! Not sure where in FL you are, but central FL and north should be fine.

It will be a crape myrtle until and unless it becomes bigger than you wanted, at which point it starts becoming a "Cripes!" myrtle.

But it will never be a crype myrtle.

In ref to crape Mrytle
Down the street there is a single trunk tree, that looks like a normal 25-30 ft tree, like a lolipop shape. It has a few flowers on the end of some branches that are similar to a lilac flower,
They said that it was a crape mrytle tree.
But the crape mrytles that I am familiar with have multi trunks with the branches arcing over toward the ground.
Are these tree types a different species of crypte mrytle, or something else entirely ?

There are a billion different cultivars of crepe myrtles. Most want to be shrubby bush/trees. If you prune them consistently you can obtain the tree shape from some.

Red maples will want to be trees. Open grown occasionally you will need to prune a branch.