I was able to access http://localhost:631 (note: printer must be "on"), but it took me to the CUPS Home page. Info about the non-profit organization.

The only items that seem to be related to my printer—Administration, Printers—were disabled, but there was a command shown that would turn on web page viewing of these resources.

On a Mac since 1984.
Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.