72 is the biggest it can go in Word when selecting from the font drop down list.
However, you can type in any size you want from 1 to 1638 points - probably way larger than you will ever need seeing as the maximum page size is limited to 24 inches.
Shortcuts for growing/shrinking fonts are (with the text selected):
Ctrl+[ = increase in 1 pt increments
Ctrl+] = shrink in 1 pt increments
Ctrl+Shift+> = grow in increments as listed in the font drop down list, thereafter by 10pt increments
Ctrl+Shift+< - shrink as above
Ctrl+[ or ] are particularly useful when micro-fitting a word or title to fill a given space.
Regards: Terry