In previous Halo games, the task selection menu allowed you to replay story missions and thus complete incomplete achievements more easily, but Microsoft has confirmed that Halo Infinite does not have such a feature. So there’s no such thing as a replay of a mission in Halo Infinite, so if you want to replay story missions, you should open a new record and start over.
If you like to finish games 100%, you should plan accordingly when playing Halo Infinite and make sure you don’t miss anything on missions that don’t have the possibility to return.
After passing the first two missions, the game goes into an open-world mode, and a Microsoft spokesperson says that “it is not possible to repeat the first two tasks in the same recording file”. Main story missions can only be played once per recording.
However, because skull, one of the collectable items, is linked to the player account, when you start a new record, what you collected in previous records doesn’t disappear.