Also i'm surprised noone said future. It's a floor wax, which is close to a lacquer. You can make it flat by adding tamiya's flat base. It's the 'standard' gunpla clear coat.
I build and paint guitars, so i know alot about finishing. If i do gunpla again. (i currently am not.) I'd use a waterbased acryllic lacquer. Target coatings has some good stuff. Might be a bit expensive. The touch up car lacquer (duplicolour) is great bang for the buck.Krylon has changed their formula far too many times. It should be fine for gunpla, but personally i would never touch that crap. You have no idea if it's even going to be compatible with itself.
If you can only find gloss coats, try roughing it up with 0000 steel wool. It should give the paint a flat/satiny appearance. It'll also add a bunch of tiny little scratches, so practise it on something to see if you like the look.
My advice is just make sure your topcoat is compatible with your bottom coat.
Someone buy me a kit, so i can try this out for myself haha.