YES OCP

Phone.cs

public abstract class Phone
{
    public abstract void Make();
}

public class Iphone : Phone
{
    public override void Make()
    {
        Console.WriteLine("Iphone Created\n");
    }
}
 
public class Samsung : Phone
{
    public override void Make()
    {
        Console.WriteLine("Samsung Created\n");
    }
}

public class Xiaomi : Phone
{
    public override void Make()
    {
        Console.WriteLine("Xiaomi Created\n");
    }
}