If you’re using Node-Red then the communication path should be…
ESP32 <—> Node-Red via MQTT
Node_Red <—> Blynk via the Blynk IoT contrib
No certificate needed, just the Blynk Auth token which you get when creating a template then a device in Blynk.
I’d start by reading this topic from start to finish. It was originally written in relation to Blynk Legacy, but the later posts bring it up to date with Blynk IoT (but don’t skip straight to the end, it won’t make sense)…
You might be using Arduino IDE to write the MQTT sketch that runs on your ESP32, but the rest of the work will be done in the Blynk web console and mobile app, and in Node-Red.
Pete.