So far there’s basically one outfit for each faction available. You get one from the settlers, one from the raiders, one from the blood eagles (Beckett side quest), and one from the Blue Ridge Caravan (riding shotgun event) as well as a few misc ones like the Chinese stealth, secret service armor and under armor, and the radiation suit the scavengers in emmet mountain disposal wear

The rest of the outfits are future atomic shop releases...