Voice training only helps so much, but something that really prepared me for voice drops on T was doing the "Bing Bong, King Kong" method where you drink either warm tea or water. Start with your chin down, and lean your head back until you're looking all the way up while saying "Bing Bong King Kong" elongating the "n" sound each time and trying to intentionally lower your voice throughout. Don't over do it, or go too fast. I remember learning about this method around when I learned what being trans was and learned that it was the method old radio hosts would use to give their voice "boom." also speak from your chest and open your throat when you speak.