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

{
  "type": "minecraft:smelting",
  "category": "misc",
  "cookingtime": 200,
  "experience": 0.15,
  "ingredient": {
    "tag": "minecraft:logs_that_burn"
  },
  "result": {
    "id": "minecraft:charcoal"
  }
}