From GameWatcher: “The Sinking City may have you face off against otherworldly horrors, but that doesn’t mean you can’t look stylish along the way. Outfits come in droves here, and we’ll teach you how to get all costumes easily, without having your brains eaten out of your skull.
Down below, you’re going to find pictures of all costumes in The Sinking City, as well as a short tip on how to get them. Find whichever one you like most, and get to it! Keep in mind that you can equip whichever outfit you have unlocked at Reed’s hotel room, in Devil’s Reef.”
Source: N4G PC The Sinking City Outfits – How to unlock all Costumes