For setting custom logo the Clarity documentation suggested to go to Admin --> System Settings. But we do not see an option for System Settings in our login to clarity.
Clarity 16.1.0
The modern UX (clarity) administration menu > system setting module as shown in the screenshot should be available with the necessary admin security access right. The security access right Administration - Application Setup -would need to be ideally provided for the clarity admin user who needs access to this page, the right can be provided from Classic PPM > Administration.
For more on the access right visit Administration access rights