Good API: https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/resource-groups/client/tag.html

tags.py

import argparse
import boto3

from datetime import datetime

DEFAULT_REGION = "us-east-1"
DEFAULT_RESOURCE_LIST = ["arn:aws:s3:::cow.mothersect.info",
                         "arn:aws:lambda:us-east-1:441882069681:function:YvonneGo", ]


def setup_args():
    args = argparse.ArgumentParser(description="Tag Test")
    args.add_argument("--profile", dest="profile", required=False)
    args.add_argument("--region", dest="region", required=False, default=DEFAULT_REGION)
    return args.parse_args()


def main():
    args = setup_args()

    if args.profile:
        session = boto3.session.Session(profile_name=args.profile, region_name=args.region)
    else:
        session = boto3.session.Session(region_name=args.region)

    tag_client = session.client("resourcegroupstaggingapi")

    tags = tag_client.get_resources(ResourceARNList=DEFAULT_RESOURCE_LIST)

    print(f"Tags: {tags}")

    dt_tag = datetime.now().strftime("%Y-%m-%d-%H-%M-%S")

    update_tags = tag_client.tag_resources(ResourceARNList=DEFAULT_RESOURCE_LIST,
                                           Tags={"dt": dt_tag})

    print(f"Update Tags: {update_tags}")


if __name__ == "__main__":
    main()