Is your feature request related to a problem? Please describe.
Not really. It would be nice to be able to insulate ALL armor instead of just chainmail. Endgame, there shouldn't need to be a sacrifice between defense against damage and defense against cold.

Describe the solution you'd like
Maybe an template like the chainmail one, but harder to get, that allows any armor to be padded.

Describe alternatives you've considered
A type of fur padding that's harder/rarer to get, that can be used to insulate all armors.

Netherite already provides insulation (though, not as much as fur-based armours). Sacrificing armour for other benefits is at the heart of many mechanics in Minecraft, throughout the early, mid, and late game (For example: Elytra, Gold Armor in the Nether, Leather/Fur Boots in Mountains, Turtle underwater). If you want to adjust things for your own mod pack, you can use the Thermoo item attribute modifiers API (in 1.20), or Armor Material Tags (in 1.21).