On Windows 10, the ability to change font size across the entire system has been available in previous releases, but starting with the version 1703, the option was remove for some reason.
Since then, the only way to change the system font size was through third-party tools, which isn’t a convenient solution. However, the option is coming back with Windows 10 version 1809 (October 2018 Update) to change the font size for title, Start menu, message boxes, palette titles, icons, and tooltips for all apps.
How to change text size on Windows 10
If you must make the system font bigger on Windows 10, use the following steps:
Click on Ease of Access.
Click on Display.
Under “Make text bigger,” use the slider to select the font size you want.
Click the Apply button.
Once you’ve completed the steps, the size of the font will change across Windows 10 and apps.
If you don’t see this option in the Settings app, it’s because you’re not running the version of Windows 10 that supports this feature. The ability to adjust the size of the font is available with Windows 10 version 1809 (October 2018 Update) and later releases.