Board support has just been merged, but won't appear until the next platformio-esp32 stable release (see
https://github.com/platformio/platform-espressif32/pull/1344).
For now, you can create a project with an existing ESP32-S3 board (for example the Adafruit ESP32-S3 Feather)
and then once created, edit the platformio.ini:
[env:esp32s3_powerfeather]
platform = https://github.com/platformio/platform-espressif32.git
board = esp32s3_powerfeather
framework = arduino ; or espidf
However, this will use the latest development version of platformio-esp32 instead of the stable version (see https://github.com/platformio/platform-espressif32?tab=readme-ov-file#usage).
