FWIW it’s located in my Arduino/libraries/Seeed_Arduino_LCD folder. I also have a LGFX_TFT_eSPI.h file located in a different directory (Desktop/LovyanGFX/src ). It has this code:
#pragma once
#ifdef __cplusplus
#include “LGFX_TFT_eSPI.hpp”
#else
#error LovyanGFX requires a C++ compiler, please change file extension to .cc or .cpp
#endif