By "pack", do you mean checked baggage for flying? If so, here is what we do.
We have a standard 7 ft. diameter 2-pc beach umbrella and a good HD screw-in plastic sand anchor to hold it. You really have to have an anchor for Florida sand; it is too fine to hold up an umbrella on its own, no matter how deep you dig. However, an umbrella with a built-on sand anchor is not good for flying, because it makes the lower part of the pole longer, and those tend to have a sharper point, which can puncture luggage. Our umbrella pole bottom piece is plain, and is 40", still too long to fit in any of our pullman suitcases, so I bought this duffle bag to hold the beach gear:
https://www.amazon.com/gp/product/B00LY0HWFQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
The duffle is within airline size limits
as long as you do not stuff it more than half full. (You need to keep the diameter to no more than 12", because the length is already 40", and the maximum airline standard-size allowance for checked bags is 52" combined.) We put the umbrella, the sand anchor, our water shoes, 2 straw mats and 4 beach towels in it; folded lengthwise and skinny. The towels keep the umbrella from getting bent going through the bag room. I keep it hanging in the garage already packed, so we just grab it on the way to the airport. We almost always fly SWA, where there is no charge to take it.
Note that the SportBrella mentioned above is too long to check without paying an oversize fee; both models of SportBrella are. (Great beach umbrellas, but not great for flying.)
Your other option is a pop-up beach shelter with a wire frame and sand pockets. We have one of those from Ikea, and it will fit in a 29" suitcase, but only if I deliberately over-fold it into 3 loops instead of the normal 2 loops. This is a bit wearing on the frame (and I gave myself a black eye once when it popped back open on me when I was folding it), so I tend to prefer using the umbrella duffel instead. However, the shelter can be a viable option if you are on an airline that charges extra for baggage, because you can put it flat in the bottom of a 29" bag. (Target also carries similar shelters, and the ones around here still have a few left in the clearance aisle now, at the end of September.)
EDITED to add one other option: I've been seeing these lycra shade tents at beaches lately, and they do fold small. Bit of an exercise to put up, though it does provide more shade than a standard umbrella, Also something of an investment; but if you often fly to beaches, that isn't normally an obstacle. I think that I would add a short sand spade to the kit if I used this; the sandbags probably need to be buried to be really stable.
https://www.amazon.com/Neso-Anchor-...abana&qid=1569601857&s=sporting-goods&sr=1-12
