minecraft-assets/assets/minecraft/blockstates/water_cauldron.json

{
  "variants": {
    "level=1": {
      "model": "minecraft:block/water_cauldron_level1"
    },
    "level=2": {
      "model": "minecraft:block/water_cauldron_level2"
    },
    "level=3": {
      "model": "minecraft:block/water_cauldron_full"
    }
  }
}