The Etruscans didn't have any sophisticated system of writing, which meant that there aren't many documents that we have that state how they ruled(There are some but we don't know if it came from the Etruscan empire for sure). Just so you know, the Etruscans and the Romans aren't necessarily separate. They actually ruled over Rome for around a century and then left for unknown reasons. During this time period, Roman philosophy, art, architectures were also at their peak
Hope I helped :)