bedrock-samples/resource_pack/render_controllers/slime_armor.render_controllers.json

{
  "format_version": "1.8.0",
  "render_controllers": {
    "controller.render.slime_armor": {
      "geometry": "Geometry.armor",
      "materials": [ { "*": "Material.outer" } ],
      "textures": [ "Texture.default" ]
    }
  }
}