Its possible to create a model with objects inside using Entity Framework Core?

Question

I mean, at the moment of creating the model, it is automatically created with one or more objects.

I thought about creating a service with a list of objects and inserting them, then declaring them as a singleton in program.cs, but I'm not sure if this is correct or if it will work.

I'm trying to do this with my Rol.cs class:

public class Rol : Entity
{
    public string Role { get; set;}
    public string Description { get; set; }

    public Rol()
    {
    }

    public Rol(string nombre, string descripcion)
    {
        Role = nombre;
        Description = descripcion;
    }
}

I want to have the roles of the users already defined.

Could anyone tell me if it's possible or if I'm wasting my time with it?