example.comcannot be tied.
To connect a domain to Google Sites (instructions from google), do the following:
www.example.comin this field you should specify
Additionally, you can configure the site to work at the main address (without www) by redirecting requests to the site from www.
To set up a redirect, enable straight webredirect and in the field “URL for address»Enter the address of your site from www.
As a result, there will be the following scheme of site availability: