With it now being harder to just check a website for Cosmetic IDs, I thought I would datamine the IDs and then make a post once I understood how to do it.
There are 2 ways to find the new content IDs. If you want to get the IDs as soon as the updates drop, you will need FModel.
First Method: FModel
Download FModel, open source ****** .pak file explorer, and navigate to your DBD pak files. I recommend opening all of the .pak files you have for easier access to the IDs.
To find the Cosmetic ID you are looking for, go to DeadbyDaylight/Content/Data/Store then Campers or Slashers, find the character you are looking for, extract the CustomizationItemDB.uasset and use Ctrl+F to find the name of the item you need (single items preferred, sets sometimes don't appear)
An Example for Clown's new Easter Skin:
https://imgur.com/a/pbzsKjg
Second Method: ****** PakTrack
Go to
https://******.com/jesterret/DBDPakTrack and use this database the same way as explained for FModel. Go to DeadbyDaylight/Content/Data/Store and select your characters CustomizationItemDB.uasset and use Ctrl+F to find the name of the items you are looking for.
Example:
https://imgur.com/vL65vXh
All of this info comes from the great people the leaksDBD subreddit, if you need more info they have a datamining post pinned for you to look for more info.
Please don't bother the admin with questions on this stuff.