Although it has become common for folks to change the appearance of their car to matte using XPEL Stealth by covering every panel, its main purpose is protecting matte finishes. Until this type of product came to the market, people who bought a vehicle with a matte paint finish had no way to protect their paint without changing the appearance where it was covered. As someone else stated above, using glossy film on a matte finish will make the surface glossy, just as using matte on a glossy finish will make the surface matte.
To the original poster, if you have access to a vehicle with the frozen finish (or even a painted swatch) I can send you a sample of Stealth so you can see what it would look like. This may help you decide which way to order the car.