Sometimes, if you get given a bike or can pick something up locally for a silly cheap price, it can be worth taking a punt on a size you wouldn't actively go out looking for normally.
I'm just over 5' 11", and my ideal fit size is 23" or 23 1/2" - much smaller and I generally find the bars are too low and there's too much seatpost on display, which just looks wrong on steel road frames!
One day a couple of years ago, I spotted a nice 531 framed flat bar Raleigh for sale. There was no size mentioned in the advert blurb, but the photo looked like a "goldilocks" frame that at least might fit me, so I took a chance as it was only beer money anyway.
I ended up with a very nice 22 1/2" hybrid, which just needed the seat a bit higher and the bars up more, than I'd normally prefer. The reach was a tiny bit short but I mitigated it largely by moving the saddle back a bit on it's rails. Rides very nicely. Wouldn't have actively sought out one listed as that size, but it was in the right place at the right money.
If you get one the wrong size and it wasn't overpriced, you should be able to move it on at no loss if needs be, and replace it with something else that fits better. Apart from a bit of messing around, you are unlikely to be much, if anything, out of pocket.