Developing breasts without HRT, yes but they also use drugs with side effects.
Other things you could do is exercise, have laser/electrolysis, longet hair, pair of small jewel earrings, voice training, tucking, and wearing appropriate clothing.
However, if you were planning SRS, if you can find somebody that will take you with having had no HRT; you will need it afterwards. As your body will not produce enough on its own to be healthy.