Hello
700c is the modern standard for rim size, 32 is the tire width.
32 is already pretty fat but you can put skinnier tires such as 21-25 known usually as "road tires"
I used to own the 7.2 fx and for most (city) purposes a 700x25 is a great compromise.
I believe the fatter you can go with those rims are about 40ish and definitely you do not have change rims just tubes and tires but a second wheelset can become really handy for say a "cross tires" for dirt paths.