There is a certain amount on customisability of these font sizes.
Go to the UI button at the top right of the screen in EVE and open the user interface you use.
Then, on the resulting User Interface form, go to the Options tab and you’ll see as below where you can adjust sizes
Might be wise to take a screenshot of the settings as they are now before you start doing too many alterations so you can always revert to these.
Category: Setup, Settings and Options