You are, I think, referring to a sort of 'Auto-Tune' ability...?

I'm afraid the G70 does not have an 'auto-tune' mode. You HAVE to provide it with a track that contains the melody you want sung, unlike Auto-Tune, or the TC Helicon stuff, which recognizes what pitch you are singing, and automatically re-tunes the voice to the nearest half-step (or scale degree).

However, this works well on SMFs where you want a specific harmony part that either has dissonance with the chords, or runs in a counter melody to the main one.

But without EXTENSIVE work on all your SMFs, it isn't much use as a general 'tune-up' for all your singing. A stand-alone unit from TC or Digitech is probably a good way to get this....