Let’s imagine that you need to restrict to secure your whole site, or only your Content Management instance. No anonymous access. As a Sitecore old school guy I tough about site requireLogin setting set to true and loginPage to /sitecore/login
From old Sitecore Developer Network
It changes with Sitecore 9.1 and Identity Server . A must read article, Understanding Sitecore authentication behavior changes, says that the new format is /identity/login/{your_sxa_site_name}/SitecoreIdentityServer.
