Hey there!
I believe New Universal Login page supports login_hint
parameter.
You can specify the
login_hint
when redirecting to Auth0, and it will be used to populate the username/email field for the login or signup page.
I did a quick test which seems to be working.
https://[Tenant].auth0.com/authorize?client_id=[Client ID]&response_type=token%20id_token&redirect_uri=https://jwt.io&scope=openid&login_hint=user1@gmail.com&state=1234&nonce=5678```