I have been an alto since I started singing in a choir, and I know that I do have a very wide range, and can sing very high, but it sounds bad. I can reach most of the high notes pretty easily, but I’d like some advice and exercises to help me develop a nice, mezzo-soprano tone.
My teacher always says that it doesn’t matter if you reach a note, it’s how good it sounds. Sopranoism comes from mainly the head voice, so its not the diaphragm pushing all the air, it’s also the upper throat. Try asking a vocal coach to help you or you could harm your voice.