OpenID Connect Enterprise Connection many email domains

Thanks for that. I will probably not describe this very well as this isn’t my area of expertise. We have Auth0 providing SSO for a couple of apps. We also have an OpenID Connect enterprise connection “trusting” (I’m sure that isn’t the right term) an Okta instance. We now have the need to integrate with another Identity Provider. That providers email domains could be thousands and change constantly so I don’t think we can utilize Home Realm Discovery like it is out of the box. Ideally, we’d like to avoid the user (once authenticated to the third party IdP) to not have to re-enter their username. I was wondering if maybe I need a different type of connection or flow or if there is a way to pass the connection id from the third-party idea. I’m trying to determine options. Any shove in the right direction would be appreciated.