If by engineered you mean a sound engineer was involved, then sure. There's usually a delay effect on his vocals. But if you're implying there is auto-tuning, there isn't.
No. What I mean is we haven't actually heard his voice WITHOUT it being "engineered". Or processed.
I have an acquaintance that does sound engineering for big acts in Vegas, he posts (via private channels) what comes in and what goes "out".
You can tell the difference, once exposed.
For instance: this is kinda bad:
I'd really like to hear this guy clearly.