Based on my understanding you want to check if the type is a list and if the list’s elements is type X.
You can do the following:
        var type = (new List<int>()).GetType();
        if (type.GetInterface("IList") != null && type.IsGenericType
                && type.GenericTypeArguments.Length == 1
                && type.GenericTypeArguments[0] == typeof(int))
                    Console.WriteLine(true); //Outputs True
3
solved Item type from a list type c# [closed]