How to call the get user from custom database using ASP.NET Core MVC? & Can I access the callback result of Login from custom database?

Hello everyone.
I’m new to Auth0 and not that strong in programming I’m in learning phases.

My first question:
How to call the get user from custom database using ASP.NET Core MVC?
Since I’m using MySQL Database I use custom database so I want to retrieve some user information from the Get User inside the custom database but I don’t know how to call it since the sample could contains only how to call the Login from custom database.

My second question:
Can I access the callback result of Login from custom database?
I mean exactly can I get these information into claims so I can use them in my code
return callback(null, {
user_id: user.id.toString(),
name: user.username,
email102: user.email,
role: user.role_d,
is_active: user.is_active

Thank you in advance