Honestly, you'll need a vocalist that has practiced a lot with auto-tune,

his lead vocals are pretty upfront most of the time, it is filled with the usual backup doubles vocals.
first, it's gated to take out mouth noises, then it's boosted in the top end cut unnecessary rumble.
next it is compressed a lot with a fast compressor too smooth out sudden peaks.

Next, his extras are generally processed the same way, but with an extra dose of fx:
moving pan, distortion, extra verb, the low-cut is usually bit higher in terms of frequency to make it less interfere with the lead vocal.

Generally, the doubles are mixed in to be barely noticeble, the extra's are just below the lead vocal.
It could look something like this:

LEAD: 100%
Double Left: 25%
Double Right 25%
Extra 75%

Group it together, add a smush delay (usually tempo synced). add a slow compressor to balance out overall level.

If done right the vocal looks like an sausage without sounding overcompressed (relative too fatty's records ofc)

Good luck!
you can always ask for more advice