From the limited amount I know about these things I would say 'yes' it's possible. I would guess that the first thing that could be done would be to double the vocal and add a tiny amount of delay - that usually thickens a vocal sound. With a little judicious use of EQ you could boost some parts of the voice which would give a bit more depth.

There was a thread on here some while back about someone who was unhappy with the results they had when they were recorded where the engineer had made the voice sound all wrong, but I can't find it.

To the best of my knowledge the person went back and said 'I don't like it sounding like that, I want it to sound like this...' and the engineer said fine and changed it and everyone lived happily ever after.