Currently it is not possible as the track player has only one volume setting that is already used for track volume. So ST3 would need to modify the audio stream in realtime which is something that is currently not done and I don't want to open that can of worms as it would make it necessary to add a whole bunch of stuff (decoding audio, buffering audio) that I don't want to touch myself and let the audio player manage.
Another point is that I already get lots of support requests related to the multiple volume settings that are already there and I don't want to add another possibility for questions like "why does my volume drop in the middle of the song?".