My husband wears a 2XLT and can sometimes substitute a 3xl for a "tall" length one but generally, we find that there aren't a lot of larger sized shirts available and when they are, the cut of the shirts just get boxier and wider but rarely longer making them too wide and too short at the same time. They NEVER carry actual tall length shirts.
For as many plus sized guests as Disney has, it continually surprises me how few larger sizes they regularly carry!!
(Sizing for women's clothing is all over the place too; if it's a "women's" / "misses" cut shirt, a small is often quite large and I have to size down to an XS, but if it's a Jr's sizing, I have to size up to a medium. And it's seemingly random which is in which size scale!)