It varies by section, but! There are a few things going on here. First, I have a vocal tract that is pretty much made of scar tissue and I’ve learned to use that - sparingly, my throat isn’t super-fond of it, I’m on acid-reflux medication permanently for unfortunate but necessary reasons - to get that kind of angry-man crackle-snarl? I’d played with that before, but I really turned that shit up to 12 for this, and figured out some new things. So using throat damage to my advantage - instead of trying to work around it - is the starting point.
Any recording project where you learn something is a good recording project, I think.
Second is purely analogue: the SM58s I have - pretty old ones, bought used - approached the right way will literally generate a bunch of low harmonics out of nowhere, low down vocal tones that I’m missing in real life. That was critical, 'cause the lowest note in that thing is the A below middle C, but the low harmonics make it sound way lower. So yeah, I get right up on that grill at the right angle - it’s almost aimed at my cheek more than my mouth really - and they start appearing, it’s neat.
You should be able to duplicate it (if you only have, I dunno, good mics or something XD) with one and two octaves-dropped duplicates of the vocal track, applied sparingly, as effects under the main vocal track.* I’ve done that kind of thing live with a POG, it’s not exactly the same but it’s close, and in studio you could definitely do better.
(Laurie Anderson used to use a pitch shifter on stage back in the day, she did some amazing things with them. I have seen exactly once a recorded performance of “The Day the Devil” she did on Saturday Night Live back in the 1980s maybe? I don’t even know, it was pretty old. I’d love a good quality copy of that performance, I’ve looked a few times and never been able to find it. I think I found the episode once, but the music performances were missing. 
)
Anyway, sorry, back on track. Then - I love the Calf plugins. I know they’re flaky, they’ve caused me trouble too, but I love what I can make them do when they behave. I’m using both their saturater and their compressor here, as well as the TAP equaliser - the one with bandwidth adjustment, 'cause that was important. I also threw on a touch - just a touch - of Steve Harris’s fast overdrive, just to raggidy things up more up front. Those also do interesting (and exploitable) things with harmonics.
Frankly I was expecting it to sound less natural than it does, and was okay with that? And soloed, it sounds less natural. But since I’m saturating/distorting everything else a lot more - plus FUCK YEAH BULLHORN 
- I think the contrast is making it sound more naturalistic in the mix. Particularly offset against the bullhorn.
So that’s how. A lot of different things. And a lot of takes. I’m a pretty good editor and I did takes across like five days to get all the pieces I wanted the right way. It was like, okay, this is half-singing, and half voice acting, let’s treat it like that. So I did. 
- I do this second-track-effects trick a lot - on Thirteen, another song, there’s a bass track that is actually two separate performances, one clean, one through trashy emulation of a really, really shitty/broken bass amp using an iRig? And then applied and mixed in the trashed track as if it were a delayed effect onto the cleaner/non-fucked-up bass, and smoothed out/merged together with hilariously short-duration reverb. That was fun. And here, too, I had an extra mic on the zouk, and I’m using a… nearly clean, heavily-high-passed copy of that second mic to put high-end attack back onto the zouk, a sharpness that got lost in all the gnarliness I was throwing onto the main recording.