renewable-resources/data/renewable/recipe/packed_ice.json

{
  "type": "minecraft:crafting_shaped",
  "category": "building",
  "pattern": [
    "III",
    "III",
    "III"
  ],
  "key": {
    "I": {
      "item": "minecraft:ice"
    }
  },
  "result": {
    "id": "minecraft:packed_ice",
    "count": 1
  }
}