example.cs

class UserAuth
{
    private User User;

    public UserAuth(User user)
    {
        User = user;
    }

    public bool ConfirmSMS()
    {
        // ...
    }
}

class UserSettings
{
    private User User;
    private UserAuth Auth;

    public UserSettings(User user)
    {
        User = user;
        Auth = new UserAuth(user);
    }

    public void UpdateSettings(Settings settings)
    {
        if (Auth.ConfirmSMS())
        {
            // ...
        }
    }
}