Kokatat drysuits are cut very, very baggy. I know that from my own (women's) suit plus a couple times earlier when I rented their Men's Small.
My husband is 5'9", about 160 lbs, and his Kokatat Medium drysuit fits him well. His waist and inseam are 32" or 33", and he is of pretty average build.
There is no reason you can't wear the size Large, of course. But there are two downsides to that: (1) Walking in too-big suits can be awkward (but OK while paddling)--you might have to hold up the suit to keep it from sagging and dragging, and (2) The bunched-over excess fabric tends to become abraded in ways that would not happen if the suit actually fit well.