As far as we know LilyGo products are fairly well supported by Arduino IDE board-system. (And less so, at least not officially, in ESP-IDF.)
So you can try to build within Arduino-IDE, probably the ‘Arduino with TFT_eSPI’ board-template in SquareLine will work for you as long as you set the board in Arduino-IDE correctly.
But if you get it all working and want to create a custom board-file that fits your board better, you can follow the instructions here: Open Board Platform (OBP) | SquareLine Studio
( Another reference to your manufacturer LilyGo can be found here: Easy getting started tutorial with Micropython and ESP32 (T-Display S3)? )