If you’re an Xbox player who owns Halo Infinite, or simply a Game Pass subscriber, you can (as of July 15th, 2022) participate in the Campaign Network Co-Op Flight, as relayed by Halo’s official Twitter account.
Halo Infinite was officially released on December 8th, 2021 for PC and Xbox platforms.
You have to join to register, which may prompt you to check back later, but once the registration is accepted, you can join Halo Infinite – Insiders group and download the flight.
Co-op and Halo went hand-in-hand during the series’ biggest era, that being the original trilogy, and Halo Reach, all of which were designed by Bungie.