YEA remove the click box and shifting rod from the hub, or put a common 20" wheel needs to be with a 135 wide axle in it,
but why bother with a bike fitting, just change the stem length to what feels better,
If what came out of the box is not satisfactory, unless you just like hanging around in bike shops..
Nature of folding bikes [other than BF] is they only make one, but adjustments of stem and saddle position compensate.

FWIW I liked working in a community bike shop where the regulars came by. WABAC ..