Yes, making funny faces to move and exercise the numerous muscles in your face can only help your singing! According to the position you are holding your mouth, a particular sound will emerge. So experiment with this. Show your top teeth on a note and then don't. You'll hear the difference. So your facial muscles must be exercised, Screw up your nose like there's a nasty smell and let go. Do that a few times until you can feel it. Raise your eyebrows and then lower them. Do that a few times. You will become much more aware of the changes you can make whilst singing.