Dear Jim,
You can achieve that way:
1/ Backup the Original Site
2/ Files: log into the control panel of your site, copy all Joomla files from the original domain’s root directory (usually public_html or a subdomain folder) and paste into the new domain’s root directory
3/ Database: Access phpMyAdmin via your hosting control panel, select the Joomla database, and export it as an SQL file.
Create a new database (for the new domain) and import the exported DB file.
Remember to assign the Database user to the new database with full privileges.
4/ Edit the configuration.php file in the new domain’s root directory, manually update the following settings to match the new database:
public $host = 'localhost'; // Usually stays the same, but confirm with your hosting provider.
public $user = 'new_database_user';
public $password = 'new_database_password';
public $db = 'new_database_name';
public $log_path = '/path/to/newdomain/logs';
public $tmp_path = '/path/to/newdomain/tmp';
Another easy way is that you can use Akeeba backup component, take a backup of your original site and restore in the new domain: https://www.akeeba.com/documentation/akeeba-backup-joomla/extracting-with-kickstart.html
Regards