def METHOD_NAME(
    subfolder: Optional[str] = None, filename: Optional[str] = None, create: bool = True
) -> str:
    """
    Returns the default config path for the platform. This will be:
        - macOS: "~/Library/Application Support/<subfolder>/<filename>."
        - Linux: "XDG_CONFIG_HOME/<subfolder>/<filename>"
        - other: "~/.config/<subfolder>/<filename>"
    :param subfolder: The subfolder for the app.
    :param filename: The filename to append for the app.
    :param create: If ``True``, the folder ``subfolder`` will be created on-demand.
    """
    if platform.system() == "Darwin":
        conf_path = osp.join(get_home_dir(), "Library", "Application Support")
    elif platform.system() == "Linux":
        fallback = osp.join(get_home_dir(), ".config")
        conf_path = os.environ.get("XDG_CONFIG_HOME", fallback)
    else:
        raise RuntimeError("Platform not supported")
    return to_full_path(conf_path, subfolder, filename, create)