How do I start co-op locally?

Never mind! I found it! For reference to other total noobs like myself, don't look in the multiplayer section.

1 - Select your game (i.e. Halo: CE)

2 - Selection Missions

3 - Make sure other controller is turned on and signed in

4 - Start game

The game does support local co op but not online co op.

I have not played it but if its anything like the other Lego titles all you will need to do is:

1, Start the game.

2, Turn on the 2nd controller synced to port 2 (player 2).

3, Press 'start' or 'A' to join the game in progress.

As I say this is a guess so if it is incorrect then apologies, but it is how all the other Lego titles have worked that I have played.

If not check on the main menu it should list the game modes, single player, co op etc.

I am doing local co-op not online

I also started playing with my cousins, it was a lot of fun. But I think due to technology and the internet it ended up distancing local co-ops from the online co-ops.

There are still many games that allow you to play with multiple people locally (overcooked you can play with 4 people).

And it's not Xbox's discretion, it's up to the game developer to think your game is a local co-op game or offline solo or online solo and so on.

I would say Realm Royale it's not a local co-op but its fun to play. Astroneer has co-op online it's in Game Pass. There's Riverbond it has local live co-op.