Using the Font>Bigger and Font>Smaller menu items you can change the size of the display font used in the main file list, the AcoustID Recording Information Window, the Action Manager, Action Editor windows, the Beatport Importer, the Chapter Editor, database viewers and notes windows, the Discogs Wizard, the Log Viewer, the Notepad, the Snapshot window and the MusicBrainz Wizard.
The above all have font sizes independent of others. You can also change the size of any multi line text field by using the same menu items. Note however, that these fields all share a single font size.
The main window and database viewer windows have status bars. You can flip the size of the text in the status bars by selecting Larger Text on Status Bars or Smaller Text on Status Bars,