How to get appsettings config data in program ?

{
  "My": {
    "Foo": {
      "Kix": 5
    }
  }
}

public class FooOptions
{
  public const string SectionName = "My:Foo";

  public string Bar {get;set;} = "default value for bar";
  public int Kix {get;set;} = -1;
  public DateTime? Pouet {get;set;} = default;
}

public static IServiceCollection AddFoo(this IServiceCollection services) =>
  services
    .AddOptions<FooOptions>()
    .Configure<IConfiguration>((options, configuration) => configuration.Bind(FooOptions.SectionName, options))
    .Validate(options => options.Kix >= 0, $"The configuration key '{FooOptions.SectionName}:{nameof(Kix)}' cannot be negative")
    ;

public static IServiceCollection AddFoo(this IServiceCollection services, Action<FooOptions> configure) =>
  services
    .AddFoo()
    .Configure(configure);

//Startup:
services.AddFoo();
// or
services.AddFoo(fooOptions => fooOptions.Kix = 12);