Volume leveling and DSP

I followed the discussion and I think I get the general idea but I am wondering how Roon choose the base line for leveling all the tracks. Is it the lower volume one in the library and Roon aim all the other songs for that level? Or is a hard coded volume level? So far I haven’t found any song that is not lowered to some extent from 3db up to 10db. Does exist somewhere in my library a song that will play without any reduction at all?
Just curious to understand.

https://kb.roonlabs.com/Volume_Leveling