Minecraft Dungeons features an online multiplayer function and local co-op. You have a variety of different ways to play with your friends, and you can choose how to best enjoy the experience, including cross-play, which will be available after the game’s launch. For those playing in a local co-op, the game does not feature a split screen function.
You and your friend share the screen as you progress through the game. There’s little reason to try and venture away from each other, so it makes for the two of you to stick together to fight off the massive mobs of enemies in the game.
If one of you venture too far from the other, one player is teleported to the other’s location. You only share the screen if you are playing in the local multiplayer mode, not online. You can automatically teleport to an ally at any time for those playing in an online multiplayer game.
When the game launches, you cannot mix local co-op with online multiplayer. You have to choose to engage with one or the other. The function to have these features running simultaneously will be available further down the line at an unknown date.
Minecraft Dungeons features a variety of loot, enemies, and puzzles you need to figure out to progress through the game. It’s certainly a much more enjoyable experience with friends, so make sure to bring as many with you who are willing to join you. The enemy mobs in the game do scale with the number of players in a game, which means having more players with you does not make it a more relaxed experience.