Instead of "emblems", there are now stickers in Call of Duty: Black Ops 4, which can be used as emblems, but can also be used in paintjobs and in the emblem editor. Stickers can be unlocked through contraband streams and reserves.
List of Stickers
Stickers
Sticker Sets
Monster Junk Food
Sweet Tooth
Pizza Fiend
Harmburger
Brain Freeze
Lactose Intolerance
Bad Dog (Bonus Sticker)
Skate Bots
Slapshot
Stick Up
Shoot Fly
Synthwave
Mystique
Astral