VanitySlots

VanitySlots is a mod that adds four extra armor slots to your inventory using the Trinkets API. The armor put in these four extra slots are what gets rendered instead of the armor you are actually wearing, meaning you can wear whatever armor you want while still looking stylish.

VanitySlots also adds four extra pieces of armor meant to hide the armor you're currently wearing. These pieces of armor can be crafted by surrounding leather armor with eight pieces of glowstone dust in a crafting table.

With a configuration option (off by default), monsters will react to what they see, NOT your equipped armor. If you have gold armor in a vanity slot, piglins won't attack you. If you're wearing full familiar armor and are invisible, mobs won't be able to see you unless you're close enough.