It's a standard 3.5-mm headphone jack. The new Mac Studio offers 3.5 mm headphone jack with advanced support for high-impedance headphones! If that is what you want to know.
Headphones are measured by their Impedance not Voltage, here's a bit more: [https://www.turntablelab.com/pages/headphone-buying-guide-what-is-headphone-impedance|Headphone Buying Guide: What Is Headphone Impedance?]