I assume you do not use do not use assistive technology like a screen reader or screen magnification program.
Here is two possible ways. Try each one and see if either works
Right Click Desktop + Choose "Properties"
In the Properties Window click on the "Appearance Tab" at the top.
In the Appearance Window click on the button called "Advanced"
In the Advanced Window choose "Item:" from the drop down list and choose "Icon" and you can choose desired Icon font size and Type.
Go to Start, Control Panel (make sure you're in the classic view)
Double click on the Display icon
Click on the Settings tab and then hit the Advanced button.
Under the General tab, you can select which DPI setting you prefer.
You can choose from Normal size, Large size or you can even make a Custom size just for you
Restart the computer (you will be prompted)
change your font size,
Go back to Start, Control Panel
Click on the Display icon again.
Click on the Appearance tab
Use the Font size drop down box to choose between Normal, Large or Extra Large.
Then just hit OK and you'll be all set.
Best of luck