It probably can be done with a lot of work and maybe fabing up some parts. It has been a while since I have been in a 2nd gen 200x and I have never had to take an sx apart but I would image it would be like doing the same thing with an older 200 trike motor and a XR motor like they did back before the 200x to gain a manual clutch. The problems I see is the crank is different between the two and you would need the right side of the 200x motor along with the right side of the crank because the sx crank is longer to accommodate for the extra clutch. On the left side you would need the sx parts because the crank is longer to make room for the starter motor drive gear.
Again I don’t have much experience with the new x and the sx. I am not even positive about the crank difference but that is where I would check if I was thinking about doing the conversion (I am thinking of doing a similar swap with my YTM).
1984 Yamaha YT 60 Tri Zinger(current project)
1983 Yamaha YTM 200 (rear suspension kit)..... long term project
2004 BMW R1150R
1972 Honda CT 70
2007 Lifan 110