Hello @Michael Menzie (Admin),
Linked based single sign on is one of the SSO methods that can be configured for enterprise applications. Generally this option shows up for applications which normally do not support any other SSO integration like SAML, OIDC. There are a lot of enterprise applications which do not support Linked based SSO configuration as they expect users to configure more secure protocol based SSO.
The SSO configuration page shows the available methods for the configuration for the particular application. It depends on the application configuration, if it supports linked based SSO the option will be available for configuration by Entra in the SSO page.