You can make any paint or finish duller by adding components but you can't go the other way. Take polyurethane for example. Satin is the exact same make up as gloss only with a satin modifier. You can notice this modifier in satin polyurethane because it sinks to the bottom of the can, you need to stir it in before you use it.
I don't think I have ever come across this modifier by itself and I highly doubt you can buy it at a paint store.