I don't think there's any special formula for this.
What i use:
Lead vocal:
I use a multi-band compressor like Waves C4
Then a vocal compressor.
a Gate
de-esser
EQ
Double Vocal ( this is the same as lead, but just tracked again )
I use the same effects + any reverb appropiate for the ocassion
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I put both tracks in the timeline, and i do an automation process in the doubled vocal.
To be more specific, i just raise the volume UP in the doubled vocal, in the sections where i want the VOX to be fuller, bigger, i mean, just COOLER.
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In chorus of the song, i do the same thing, but with 4 tracks
( i track choruses 4 times )
and i do automation to taste.
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My english sucks. Does that make sense ?