Navigate to the course and click on the profile icon on the top right corner.

From the dropdown, click "Switch role to...".

Depending on the access given, you will see all roles that you can switch to. Click on the one you want to switch to.

In the top right corner you will see which role you are assigned when in the course. Click profile picture again.

Click "Return to my normal role" once you finish checking the course in a different role.

Switch Role Function in Moodle Course