Sized around what you park
The most common mistake with carports is buying a standard size and discovering it clears the vehicle by inches. Boats and RVs are where this really bites, because the height that matters is not the hull or the roofline but everything above it: the tower, the antenna, the AC unit, the rack.
We measure what you are actually parking, ask what you might park there in five years, and design to that. A cover that is six inches too low is a permanent irritation, and widening one after the fact costs far more than getting it right on paper.
Attached sheds are worth thinking about at the same time. The structure is going up either way, and enclosing a section for mowers, tools and pool gear is much cheaper as part of the original build than as a later addition.