During the surprise Nintendo Direct Minit this morning, Nintendo revealed free content that is coming to Super Mario Odyssey this February as well as new items and ways to interact with others players.
To access the content, you will need to have completed the story mode, after this, there will be a new mode called Balloon World. By meeting Luigi at the top of a skyscraper in New Donk City, you can begin playing Balloon Mode, where you must hide balloons around the area for others to find and collect. This includes leaderboards for who can do it the fastest that will rank those who play globally.
In addition, there will be new costumes for Mario, including a Super Mario Sunshine inspired costume, a musician, and a knight. There will be additional filters added to the photo mode as well.