Google has just updated its Google Apps or G Suite account for free, as of Jan 10, 2020, we are not able to change the primary domain and add secondary for a google app account free, because google has fixed this bug.

However, you can continue to use this account by adding a alias domain, not changing the root domain is a good option, it helps account is absolutely safe.

We will hand over the root domain name (primary domain) to you along with the super administrator account.

You can send and receive emails with your domain name and use them with Outlook and apps on iOS, Android.