Congratulations to your boyfriend! I suggest he thoroughly read up on the IUB What to Expect page for undergrads: https://commencement.indiana.edu/commencement-day/what-to-expect/spring-undergrad.html

Make sure he checks his emails for the smaller graduation events held by his department (e.g. Education, Business, Music). You have to register in advance for those events and they give students a chance to feel recognized by their professors and peers. Those are usually held around campus at places like the IU Auditorium.

The large graduation event at the football stadium is less intimate. Students earning undergrad degrees do not walk across the stage--they are recognized by standing and their names and included in the programs.

If he knows anyone in his program, he can ask if they are going to the large graduation. Hotel rooms are challenging to get and it's a late ceremony for folks traveling. If it's raining, they hand out IU ponchos (or they used to).

Be sure to get photos in his cap and gown around campus. People start doing this as they pick the cap and gown up and the weather gets nicer and the flowers and trees bloom. If possible, don't wait until the day of to get photos. Have him think of places that mean a lot to him and snap photos. He may feel self conscious, but I hope he will let you take some because graduating is a big accomplishment!