This mod is for: Fabric

With this Fabric mod, you gain 4 extra slots for armor. The armor put in there will display on your character, but won't provide any defense values or other functionality. (E.g. cosmetic carved pumpkins won't protect you from endermen, cosmetic golden armor won't prevent piglins from attacking you)

1.17 and later

Requires: Trinkets API

Since Curios was discontinued on Fabric for 1.17 in favor of the Trinkets API, this mod now uses that.

The versions for MC 1.17 and higher also adds a few new features and fixes a few bugs which were in the previous version:

All modded armor should be immediately compatible without any effort from your side
The items don't show "Slot: Cosmetic Something" anymore
Heads, skulls and other "head" items (such as carved pumpkins) can now be worn in the cosmetic slot
Item tags allow you to define items which can't be worn in a cosmetic slot ( data/cosmetic-armor/tags/items/blacklist.json ) as well as items which always show and won't be overriden by an item in the corresponding cosmetic slot ( data/cosmetic-armor/tags/items/always_visible.json )

1.16

Requires: Curios API

Screenshot

By default, only the vanilla armor types are equippable.

You can add modded armor through the tags curios:cosmetic_helmet, curios:cosmetic_chestplate, curios:cosmetic_leggings, and curios:cosmetic_boots.

If you want to hide your armor using these slots

This add-on adds "transparent armor" which you can use specifically in these cosmetic slots: https://www.curseforge.com/minecraft/mc-mods/transparent-cosmetics