Well, that’s my code, that I wrote for the ESP32, and has this line near the top…
When you choose an ESP32 board type in the IDE then the compiler uses the file paths that include the core files for that board type.
If you choose an Arduino AVR board type, then different file path are used, and your compiler can’t find a file called HTTPClient.h in the AVR core files.
That’s because the standard Arduino AVR HTTP file is called HttpClient.h not HTTPClient.h.
Changing to the correct header file name for the type of board you are using should allow the compiler to find the correct file.
Pete.