Alr, kinda took me a while to respond bc of things, but here's a basic rundown!!
Lucifer- Pride. Honestly, a specific body type isn't needed, but for clothing and style, I'd say something showy. Big, bright, louderis!! And make sure that he's almost always got a big smile on his face!
Satan- Wrath. Big, burly, tough guy. Bonus points if tattoos. Usually, he's the one with the extreme demon motifs as well. For a fit, not really specific, but I imagined a stereotypical 'tough guy.'
Beezlebub- Gluttony OR Envy. Yours says envy, but I'm pretty sure Beezlebub is Gluttony, may be wrong though. But since your ref says envy, we'll go with that. Big eyes Usually symbolizes envy, also glitter. Maybe have their outfit somewhat resemble another sin or ALL of the sins, as if they're trying to be like them. If this is a modern take, (such as helluva boss, which personally, has TERRIBLE sin designs) maybe make them phone obsessed?
Abaddon- Sloth. Typical lazy couch potato. Always laying down, beer belly. I've seen sloth represented with a beard a lot, maybe go with that? Not much to say about him since he's pretty much the same in most pieces of media.
Belphagor- Gluttony. Chubby. That's all I need to say.
Asmodeus- Lust. Same thing as the last one. As long as there VERY obvious sexual motifs, you're good.
