if you use a regular short lens camera (most cameras are short lens unless you get into professional equipment), what's closest to the camera will appear larger. therefore you could hold camera a little lower and point up at your face (slight angle), it'll make your chin look bigger since it'll be closer to the camera.
pointing down will make your foreheard look bigger (giving a "youthful" look) ... a lot of girls point camera down to achieve this effect.
that's all i can say about cameras, haha. good luck!
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