Set screen to native resolution

By default, MacBook Air uses an effective resolution of 1440x900. You can increase this to 1680x1050 with the "More Space" option in System Preferences.

You can't use the full resolution of your Mac in System Preferences, but you can use some third-party applications to achieve this. QuickRes and EasyRes are two examples of applications like this, the latter of which is available on the Mac App Store. I'm sure there are other apps that can do this as well.

Intel-based Macs

Reset PRAM:  Reset NVRAM or PRAM on your Mac - Apple Support

Settings that can be stored in NVRAM include sound volume, display resolution, startup-disk selection, time zone, and recent kernel panic information. The settings stored in NVRAM depend on your Mac and the devices that you're using with your Mac.

About displays.

https://support.apple.com/en-us/HT202471

If you manage to set the resolution to 2560x1600, the text will be microscopic.