Larger sized frames did and do exist, at least in some brands; but finding one is another matter. I'm 6' and ride a three speed with a 21" frame quite a bit, and it's not too bad. I had to install a longer seat post, and even so, my hands are a little lower than my preference; but it works.
Well, that's where I started this madness. My first C&V bike was a 21" Robin Hood; I can ride it but it feels a bit cramped. I was looking for a Brooks saddle, and I stumbled across a 23" Raleigh Sports. It fits better, so that's what I usually ride. I'm looking for another 3 speed that will be easier to update than the Raleighs, with more standard threading, bracket, forks, etc. I have yet to find any other 23" 3-speed, though, so I wonder if I should keep looking or just find a 21" frame I like.
Or maybe stop the madness...
Gary