1. Sign in to Google Domains.
2. Select the name of your domain.
3. Open the hamburger menu (Top Left).
4. Click DNS.
5. Scroll down to Synthetic Records.
6. Select Dynamic DNS from the list of synthetic record types.
7. Enter the name of the resource you plan to have assigned a Dynamic IP, either a subdomain or @ for your default domain (“root domain” or “naked domain”).
8. If you selected sub-domain, enter the name of the subdomain.
9. Click Add.
10. The Dynamic DNS record is created in your list of synthetic records. Click the expand triangle next to the record to view its values.
11. Click View Credentials to view the user name and password created for this record.
12. Note the username and password created for the synthetic record. You'll need these to configure your gateway or client software to contact the Google name servers. You can edit or delete the record with the Edit and Delete buttons next to the record.

curl https://github.com/BrandenCobb/google_ddns_updater/blob/main/ddns_update.sh
vi ddns_update.sh ## Modify username, password, and hostname
chmod +x ddns_update.sh
./ddns_update.sh

curl https://github.com/BrandenCobb/google_ddns_updater/blob/main/ddns_update.sh
vi ddns_update.sh ## Modify username, password, and hostname
chmod +x ddns_update.sh
sudo mv ddns_update.sh /usr/local/bin/
sudo echo "*/5 * * * * root /usr/local/bin/ddns_update.sh" >> /etc/crontab

Never manually update your dns record again!