I'm still not sure if I'm trans or not, but I've always wanted a deeper voice. I feel so self conscious about my feminine, childish, high pitched voice, that I try to avoid phone calls, and whenever I hear my phone ring I get a sinking feeling in the pit of my stomach. I don't want to take hormones to deepen my voice, but I feel like if I could take voice lessons I'd feel less self conscious. I heard a woman on the radio who had "learned to speak like a man", in terms of both syntax/sentence structure and in altering the pitch of her voice. and I'd never known it was something you could learn. She said at work she spoke with her "masculine" voice, but elsewhere she spoke like she normally did. It was a subtle difference, but I think its something I'd like to try. I also want to be better at speeches and public oration. Whenever I look up voice lessons, the results are always for learning how to sing (something else I'd like to do, but not what I'm looking for).
Go to theatre. They teach you how to speak louder there without screaming and the same technique makes your voice deeper. But singing is useful too, they use the same technique for singing deep.