I have never seen one of the quick pop up tents that big. Generally up to 12' square at the local stores. I didn't google it before I posted, so who knows. The 12' ones are generally pretty weak.
Pretty sure the EZUp's only go up to 10x20. I could be wrong though. EZUp brand makes some good stuff. Look for ones with pull rings vs the push buttons to raise and lower them. Works a lot easier and doesn't jam as much. I'll look at a few vendors I deal with and see if I can find an actual 20x20 EZUp. That big won't be cheap though.
It's still going strong. It's a little orange from all the race dust, but otherwise fine. And it's a no-bullshit one-person setup. Pick it up from the middle, walk around it twice (once to set the top corners, once to extend the legs), and you're done. It folds up about as quickly.
But yeah, I've never seen anything bigger than a 10x20 in a pop-up. The bigger ones have separate poles that you sleeve together and then cover with a tarp.
A 20x20 would be pretty big even folded up. Think about how tall that thing would be in the center. Don't know that I've ever seen a scissor-folding style that size.
Anything wrong w/ getting 2 10x20s?
Remember also that 20x20 is one very large piece of fabric and a wind gust will take it far We have had two 10x10's blow (one at the beach before they banned them) and one at the house. The beach one didn't surprise me as much as the one at the house that was anchored down. Serious wind gusts that morning came out of nowhere. All it did was blow over but was enough to bend the posts.
For one that big, I would fill 5 gallon buckets with concrete for anchors. I'd hope they would stitch some relief "holes" into the fabric to let wind escape.