The minecraft:life_saving item component applies effects to an entity holding this item once the entity is dying.

{
  "effects": [
    {
      "id": "minecraft:regeneration",
      "amplifier": 1,
      "duration": 900,
      "show_icon": true
    },
    {
      "id": "minecraft:absorption",
      "amplifier": 1,
      "duration": 100,
      "show_icon": true
    },
    {
      "id": "minecraft:fire_resistance",
      "duration": 800,
      "show_icon": true
    }
  ]
}