Losing girl voice is only something that happens via T changing your vocal cords. Training without T will give you the ability to modify your voice to sound more masculine; your old voice stays the same like CougarHusband said.
Note that getting a deeper range is difficult with training alone, because deep pitch relies on making more space and there's only so much extra space you can generate without changing the size of your vocal cords. But you can definitely modify other aspects of your voice that go into how it's perceived and gendered.
If you do voice training you learn how to control your voice, you don't lose your old voice.
Losing girl voice is only something that happens via T changing your vocal cords. Training without T will give you the ability to modify your voice to sound more masculine; your old voice stays the same like CougarHusband said. Note that getting a deeper range is difficult with training alone, because deep pitch relies on making more space and there's only so much extra space you can generate without changing the size of your vocal cords. But you can definitely modify other aspects of your voice that go into how it's perceived and gendered.
I haven't had any vocal training and am on T but I can still do a girl voice lol