gloss coat removal

Unless your gloss coat is an acrylic over an enamel bsae, there's probably nothing you can do without also stripping the base coat.

If you can tell us what your base coat is (ie acryl or enamel) and what your clear coat is, then we might be able to make some suggestions.

if your base coat is enamel just use isopropyl alcohol. have used it a million times! it will remove the gloss/dull coat and not damage the enamel.

base coat is acrylic-gloss is testors clear coat. thank you.

base coat and model is all acrylic-gloss coat is testors clear gloss. thank you.

All acrylic pretty much means you're pooched. If it's just "too" glossy, decal as normal, and do a flat coat on top. I would suggest Future with Tamiya Flat Base as you can adjust the flat to your preference.