The measuring is done by playing a "chirp" sound that sweeps across all frequencies and recording how loud each frequency comes out of the speakers. A good microphone is needed, with a wide frequency range and preferably with a flat frequency response.
The equalization itself is not provided; It can be performed by an equalizer of your choice, such as EasyEffects for Linux, Equalizer APO and Peace for Windows, or eqMac for macOS.
It's an interesting concept and the basics should work quite well, but a lot does depend on at least having a fairly decent microphone. As this is an automated type of adjustment, what is missing is your own hearing impairments you may have.
See GitHub - erdewit/HiFiScan: Optimize the audio quality of loudspeakers
Optimize the audio quality of loudspeakers. Contribute to erdewit/HiFiScan development by creating an account on GitHub.