You can use Wokwi to simulate the ESP32, and soon also the ESP32-S2.The Wokwi is a free online simulator for electronics, and it runs in your browser. This means you can simulate code that interacts with 3rd-party sensors, display modules, LEDs and many other common parts. There's also initial support for WiFi simulation, and the developers are working on extending it to support connecting to any host on the internet (e.g. HTTPS/MQTT)