bedrock-samples/resource_pack/textures/blocks/deepslate/polished_deepslate.texture_set.json

{
    "format_version": "1.21.30",
    "minecraft:texture_set": {
        "color": "polished_deepslate",
        "metalness_emissive_roughness_subsurface": "polished_deepslate_mers"
    }
}