minecraft-assets/data/minecraft/recipe/smooth_red_sandstone.json

{
  "type": "minecraft:smelting",
  "category": "blocks",
  "cookingtime": 200,
  "experience": 0.1,
  "ingredient": "minecraft:red_sandstone",
  "result": {
    "id": "minecraft:smooth_red_sandstone"
  }
}