I’m 6’2”, normally ride a 63cm road bike, and the XL CCX is very comfortable for me. (I did buy an adjustable handlebar stem, though, to give me the ability to adjust the bars more forward.)
To share the fun of the electric bike experience, I’ve lowered the seat so that much shorter friends could ride my XL bike and none of them have had a problem fitting, even someone 5’6”. That flexibility for different size riders has been surprising to me.
If you see the measurements as to the different frame sizes, the only number that changes is the seat tube length, thus only changing the standover measurements.
The frame size doesn’t seem as critical on the CCX as on most bikes. If you can stand over it, you can ride it. On the other hand, I’d suggest going for the next larger size if you are on the borderline so there is less seatpost exposed.