I can tell you right now that its not really that super clear as it seems. There's a ton of echo and reverb added and I feel like this "live" performance has been heavily mixed after the fact. If you listen closely you can hear sections of the phrases that are much weaker and kind of whiny that they weren't able to cover up.
But you could still replicate this without much trouble. This kind of sound is very achievable without nearly as much cosmetic audio "makeup". It isn't a very technically challenging song at all.
The main thing you need to do is figure out a way to let out the sound without a lot of tension. Especially in the face/head/upper body. Think of when you call to a friend who's down the street. You're able to project your voice in a loud clear way then no problem because you don't have the tension of performing. Figure out a way to replicate that in performance free of the tension (which is what kills the sound and hurts your throat) and you'll able to achieve a much BETTER sound than this guy. You'll know you've achieved this when you feel you're skull vibrating as you sing.
