Notification.cs

public enum NotificationType
{
    Email,
    Sms
}

public interface INotificationService
{
    Task Send(IEnumerable<(NotificationType DeliveryType, string Address)> recipients, string subject, string body);
}

public class NotificationService : INotificationService
{
    private readonly ISmsService _smsService;
    private readonly SmsOptions _smsOptions;

    public NotificationService(ISmsService smsService, IOptions<SmsOptions> smsOptions)
    {
        _smsService = smsService;
        _smsOptions = smsOptions.Value;
    }
    
    public async Task Send(IEnumerable<(NotificationType DeliveryType, string Address)> recipients, string subject, string body)
    {
        foreach (var recipient in recipients)
        {
            switch (recipient.DeliveryType)
            {
                case NotificationType.Email:
                    throw new NotImplementedException();
                    break;
                case NotificationType.Sms:
                    await _smsService.Send(_smsOptions.From, recipient.Address, subject);
                    break;
            }
        }
    }
}