With G Suite, you can easily set up subdomains (or custom URLs) for each of the G Suite services, like calendar, drive, or gmail. These subdomains are in the form of:
- In Google Domains, go to the the DNS tab for your domain.
- Scroll down to Synthetic Records.
- Locate the G Suite synthetic record and click Edit to the right of the entry.
- Check Subdomains enable subdomains of your domain for matching G Suite services.
- Click the triangle next to Subdomains to select which subdomains to enable. Each subdomain will open its corresponding app, for example mail.example.com will open Gmail, sites.example.com will open Google Sites, etc
- Click Save.
For more help with custom URLs, see the G Suite Help Center.