User1120430333 posted
You would generate the EF Core Model and Dbcontext by using the EF Core database tools for EF Core DB First. The tutorial shows you how to do it starting from the "Model" topic.
https://www.codeproject.com/Articles/1209903/Getting-Started-with-Entity-Framework-Core-Databas
That I know about, there is no login pages/logic for Identity out the box, like it is for non Core ASP.NET solutions when you create the project using Identity.
I resorted to this link below that allowed me to copy/past the controllers and view into place, which allowed me to start using Core Identity. I downloaded the code that is Core 2.0 and applied it to Core 2.1.
https://www.c-sharpcorner.com/article/getting-started-with-asp-net-core-2-0-identity-and-role-management/
I never used the below link, but it may be useful, becuase once I got 2.0 login logic and views implemented into the Core 2.1 solution, the Identify database was created for the first user that was registered. I was off and running.
https://www.codeproject.com/Tips/677279/SQL-script-for-creating-an-ASP-NET-Identity-Databa
This is assuming you are trying to use MVC.