How can I safely increase the size of a door bolt?
For clarification, Is this an open door being slammed shut, or a door with clearance when latched that allows it to clatter against the door jamb?

The first can be taken care of with a gas cylinder door closer to retard the closing of the door on the last final bit.

The second can be taken care of by putting thin weatherstrip around the door to stop unwanted airflow, cushion door to door jamb contact and take up the clearance that exists while the door is latched.

I've also used felt pads for reducing the annoyance.

As to whether the bolt is big enough, it's more likely that it's the positioning of the bolt and latch strike plates that's the problem. They can also be moved towards the jamb to take up the slack clearance. It will probably take some finesse with a chisel if they're inlet into the surface along with some filling of the old screw holes so they can be re-drilled for the new strike-plate position. I mention the weatherstrip above because it's the easier of the two fixes and doesn't involve modifications that might be prohibited by your lease.