The Heltec Arduino core is not well supported in PlatformIO (issue).
And by that I mean, only hacky workaround exist to include their version of the core: This one. Sadly, they do not upstream their changes in the Espressif-made Arduino-ESP32, so they always diverge.
So, while you can create a project with targeting the regular Espressif Arduino-ESP32 core, this will not be the Heltec core that has the additions for LoRaWAN.
[env:heltec_wifi_lora_32_V3]
platform = espressif32
board = heltec_wifi_lora_32_V3
framework = arduino
is what you would use as a platformio.ini there.
As such, if you want to develop applications for the Heltec LoRa boards in the intended way, with Heltec’s Arduino core, better stick with the Arduino IDE 2.x.