minecraft-assets/assets/minecraft/models/item/elytra.json

{
    "parent": "item/generated",
    "textures": {
        "layer0": "item/elytra"
    },
    "overrides": [
        {
            "predicate": {
                "broken": 1
            },
            "model": "item/broken_elytra"
        }
    ]
}