How to prompt login when internal users access Experience Cloud Sites in Salesforce?

Enable "Separate Experience Cloud site and Salesforce login authentication for employees." in the Internal User's Profile to prompt login when internal users access Experience Cloud Sites. 

When this option is enabled, Salesforce and Experience Cloud sites are treated as separate apps. So, employees with an active Salesforce session can be required to log in again when accessing a site and employees who log in to a site can be required to log in to Salesforce.
 
 
This option will ask to login again since separate session for internal users will be required when accessing the Experience Cloud site.