Looking for logging into the Oauth2 Additional Parameter site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Oauth2 Additional Parameter site. After that you can login as usual with your login credentials.
https://community.auth0.com/t/how-to-pass-custom-parameter-to-a-custom-oauth2-connection/6709
https://stackoverflow.com/questions/7722062/google-oauth2-redirect-uri-with-several-parameters
https://aaronparecki.com/oauth-2-simplified/
https://www.oauth.com/oauth2-servers/authorization/the-authorization-request/
https://www.oauth.com/oauth2-servers/server-side-apps/authorization-code/
https://support.mulesoft.com/s/article/How-to-pass-additional-parameters-to-OAuth2-client-credentials-authorization-to-generate-a-Bearer-Token
https://developer.wordpress.com/docs/oauth2/
http://www.thread-safe.com/2014/05/the-correct-use-of-state-parameter-in.html
https://github.com/postmanlabs/postman-app-support/issues/2523
https://github.com/getinsomnia/insomnia/issues/716
https://www.iana.org/assignments/oauth-parameters
https://www.baeldung.com/spring-security-extra-login-fields
https://developer.salesforce.com/forums/?id=906F00000008tE4IAI