Using ethernet with ESP32 is very easy, thanks to the built-in RMII PHY. In this article, a simple ESP32 ethernet example is outlined.
ESP32 4G hotspot demo using Simcom SIM7600 modem (based on PCB Artists 4G Gateway), including source code and detailed explanation.
The ESP32 4G Gateway Hardware Guide for Gen.1 devices guides you through the process of identifying and programming key features.