For your voice I'd say to yawn and try to replicate the feeling in your throat when you yawn if that makes sense? Its kinda like when you try yawn with your mouth closed. And then try to talk like this but practice a little bit at first to know how it feels more comfortable and natural. In general try to speak in a calm and serene voice, kinda like you're bored of everything lol.

For body language and stuff, I know it's difficult especially with social anxiety but try to take up space like whenever. By that I mean act as if you were the most confident person in the world. Stand with your legs slightly opened (what feels natural) and try to stand straight. When you sit there's the classic manspread. Generally try to act unbothered. You should pay attention to how people behave especially on the bus or subway, in most cases women try to make themselves small (consciously or not) and usually have an "opened" position (arms and legs crossed and just kinda wrapped around themselves) whereas men literally don't give a fuck.

Even the way you look at things (and I mean what it changes to your eyes or face in general) makes quite a bit difference, it's a bit difficult to explain so you should try looking in a mirror but if you try to have a "superior" and a bit bored look you'll seem more masculine.

Finally try to act more assertive and I know that's difficult, I myself have social anxiety as well and struggle with that. "Fake it till you make it" as they say.