As far as voice, depending on how old "he" is, hormone replacement might not change that. If it’s in the early teenage years you have a chance for voice changing, otherwise voice training. That’s one thing there is no pill/surgery for.
Muscle development, definitely.
Male characteristics, that would depend from person to person.

There are plenty of alternatives to testosterone boosting besides TRT. Herbal supplements aren’t something to take lightly, but if you go that rout you won’t have a doctor’s help and will have to largely make most of the decisions yourself after research. I’m don’t have personal experience with these herbs, being a girl, but gourana, horny goat weed, even saw palmetto in high enough doses. Most vitamin stores have entire sections for male support.

But if your main concern is voice, TRT probably isn’t going to work in an adult to deepen the voice. Good chance with someone younger, but we can’t always turn back time. Making a voice masculine isn’t always deep, tonality is important too. You could be in a bass range and sound like a girl, or soprano and be manly. Voice training, if you want the help of someone else, they do have voice therapy.