ListPatterns.cs

using System;
using System.Collections.Generic;

var numbers = new List<int>() { 1, 2, 3, 5, 8 };

// List pattern
if (numbers is { 1, 2, 3, 5, 8 })
{
    Console.WriteLine("Fibonacci");
}

// Property pattern
if (numbers is { var first, 2, 3, 5, var last } && first == 1 && last == 8)
{
    Console.WriteLine("Very special Fibonacci");
}

// Slice pattern
Console.WriteLine(numbers switch {
    { 1, .., var sl, 8 } => $"Starts with 1, ends with 8, and 2nd last number is {sl}",
    { 1, _, _, .. } => "Starts with 1 and is at least 3 long",
    { 1, .. } => "Starts with 1 and is at least 1 long",
    _ => "WAT?"
});