Tribes of Midgard local co-op is unfortunately not in the game, and players looking to have some couch co-op can really only do so online.
Tribes of Midgard Local Co-Op: How to Connect
Tribes of Midgard currently does not support local co-op, but does support an online co-op mode where you can grab a tribe of up to ten people. You and your friend wanting to explore Norsfell, or your entire dorm's floor - and everything in between.
Depending on your preferred platform, whether it be PC, PlayStation 4, or PS5, utilize that platforms invite system to start forming a tribe of your own.
Keep in mind that Tribes of Midgard currently does not support crossplay of any kind, so if you are a PC player, you can only play with your friends on PC, not anyone on either PlayStation system.
Tribes of Midgard is available for purchase right now on Steam, PlayStation 4, and PS5.