I've had three different highchairs over the past 30-odd years. When I was young and very thin, my ex bought me a Cosco folding highchair as a Christmas gift, then fed me in it for a year or so. At that time, Cosco was also making wood highchairs, and they had a very large model that would actually fit an adult. I remember sitting down in it in a baby store near us and the saleslady offering to slide the tray on. I think she might have had an idea that a 'big baby' would be using it.
I kept the Cosco wood highchair for about a decade, and had to part with it when I moved. I recently spent $425 and bought a very b-i-g highchair (again, wood) from an Etsy vendor. The seat height is 30" - you should sit on top of your washer or dryer as a comparison - and my nanny had to use a step stool to get to a comfortable height to feed me. But once you're strapped in it and the tray is on, the thing is so massive that you feel very little.
It's easy enough to take apart and store, but I'm not sure how long I'll keep it. As Trevor noted, I'd rather have a folding metal one again. Finding those in a size big enough to fit an adult is, however, very problematic.