minecraft-assets/assets/minecraft/blockstates/sand.json

{
  "variants": {
    "": [
      {
        "model": "minecraft:block/sand"
      },
      {
        "model": "minecraft:block/sand",
        "y": 90
      },
      {
        "model": "minecraft:block/sand",
        "y": 180
      },
      {
        "model": "minecraft:block/sand",
        "y": 270
      }
    ]
  }
}