Unless the game uses vsync as a frame limiter then it is not possible for dxvk to override it as it will happen internally in the games own code.
Edit: You can ofc still make the FPS be lower via a external limiter, but not uncap it outright.
Nothing extracted yet.
I don't know if it is technically possible, but it would have been great if there was an optional setting in dxvk to try to forcefully unlock the frame rate of any game.