USB to ethernet chips like LAN7850 require GPIO to RESET pin?
It isn't necessary as USB has a provision built into the protocol for the host to initiate a reset. This is how it would be used if, for example, the device were a USB-to-LAN dongle.

However, you should have a reset to the IC that is held down until after the LAN7850 power becomes stable.

As a nice-to-have, OR-ing the power-on reset with a GPIO reset might be useful for testing or for power management.