minecraft-src/data/minecraft/worldgen/template_pool/village/common/sheep.json

{
  "elements": [
    {
      "element": {
        "element_type": "minecraft:legacy_single_pool_element",
        "location": "minecraft:village/common/animals/sheep_1",
        "processors": {
          "processors": []
        },
        "projection": "rigid"
      },
      "weight": 1
    },
    {
      "element": {
        "element_type": "minecraft:legacy_single_pool_element",
        "location": "minecraft:village/common/animals/sheep_2",
        "processors": {
          "processors": []
        },
        "projection": "rigid"
      },
      "weight": 1
    }
  ],
  "fallback": "minecraft:empty"
}