How to get your vocals to sound fatter and more powerful like a pop comercial track?

[Resurrect]

Doubling means recording it twice. Yes, you have to sing it pretty much the same both times. It's a common technique with vocals and guitars.

So recording it again through the studio monitors wouldn't do the trick?

 

[RFR]

Not really, you would just have two identical mono vocal tracks. Pretty much only difference would be how the monitor translates the live vocal sound.

Doing it again will give you subtle pich, tonality, time changes. Etc. This will fatten it up.
No matter how perfect the singer sings the second track, it WILL be different.