I think that the beds in the Paradigms and Valors King standard with Queen optional. And the Avenue is Queen standard with King optional. Take a look at the floor plans on their site.
https://www.alliancerv.com
If you buy a unit with a queen, there is a difference in some of the dimensions of the furniture on the sides of the bed. It will take some work to modify things to fit a king. Also I don't know if the base is the same dimensions between the 2 with a different size platform or if everything is different.
Bottom line, IMHO, if you want a King, you'd be better off looking for something with a King instead of trying to switch later.