bedrock-samples/resource_pack/textures/items/field_masoned_banner_pattern.texture_set.json

{
    "format_version": "1.21.30",
    "minecraft:texture_set": {
        "color": "field_masoned_banner_pattern",
        "metalness_emissive_roughness_subsurface": "field_masoned_banner_pattern_mers"
    }
}