minecraft-assets/data/minecraft/trim_material/netherite.json

{
  "asset_name": "netherite",
  "description": {
    "color": "#625859",
    "translate": "trim_material.minecraft.netherite"
  },
  "ingredient": "minecraft:netherite_ingot",
  "override_armor_assets": {
    "minecraft:netherite": "netherite_darker"
  }
}