If you want to switch between WiFi and Bluetooth then it will be far from simple.
The nearest readymade solution is this for the ESP32:
Given your follow-up question about ESPSoftwareserial I think your next move should be to spend a lot of time learning, experimenting and becoming more familiar with C++ programming in general and Blynk in particular and learning through trial and error.
This forum is great for people who have developed those skills and just need signposting in the right direction with a potential solution. You aren’t at that stage yet, and that’s where you need to get to to best usilise the resources of this forum.
Pete.