Welcome to the Auth0 Community!
SSO between application should work seamlessly as long as both applications have the same database connection enabled for user storage. In that case, an user already authenticated through App1 will be already logged in into App2 with the same user profile.
You can read more about that in this here:
- How to Achieve Single Sign-On (SSO) Between Applications
- How to Implement SSO for Multiple Applications
If you have any other questions, feel free to leave a reply!
Kind Regards,
Nik