For Forge 1.16.4:
Please add a GUI Button (or at least a keybinding) to swap between the cosmetic armor and the equipped armor: (I am not referring to show/hide cosmetic armor feature)

Steps to reproduce:

1. armor set 1 is equipped
2. armor set 2 is equipped in the cosmetic armor slots
3. press the GUI Button to swap (or a keybinding)
4. armor set 1 becomes unequipped and cosmetic armor becomes equipped
5. armor set 2 becomes equipped in the cosmetic armor slot

Purpose:
I and my other players on the server found a secondary use for the cosmetic armor slots:

1. to keep a set of gold armor for the nether, inside the cosmetic armor slots. However, we have to manually remove them from the cosmetic armor slots, then unequip our actual armor, then equip the armor that was once in the cosmetic armor slot, and then also equip the armor once equipped, into the cosmetic armor slots.

Thank you!

I would love to have that in the (Neo)Forge 1.20.1 too please, a keybing to quickSwap armor would be awesome :D