Imagine a scenario:

1. I am the admin of Power Pages and is responsible to support end users who raises the portal issues, this is quite normal if the portal is for internal users.
2. then i have to contact the affected user to get more details and ask the affected user to repro the issue.
3. I am asking for a feature for impersonation like "login as a specific user".
4. Actually this feature exists in Salesforce. more details is as below:

https://help.salesforce.com/s/articleView?id=sf.logging_in_as_another_user.htm&type=5