There is no "T-Display-S3" board in Arduino or PlatformIO that pre-configures everything. LilyGo leaves you in the trenches, with the need to select a GENERIC "ESP32S3 Dev Module" (ie esp32-s3-devkitc-1) board... but this is INSUFFCIENT without configuring it further!
It is literally titled: "Espressif ESP32-S3-DevKitC-1-N8 (8 MB QD, No PSRAM)"
... no PSRAM, eh? Whelp, T-Display-S3 has 8MB of PSRAM. We have no idea if said ram is QSPI (Quad), or OPI (Octal), but either way, it's DISABLED by default! Strike One: LilyGo does not provide sufficient documentation on this board to even configure it properly!
In Arduino IDE you can configure this from the Tools Menu, and use the Not-Hardly-Pass-As-Documentation official screenshot of the config shown in the Github page for the T-Display-S3. Great... but in PlatformIO... you're SCREWED. It is not evident at all how to configure this thing!
BTW: Adafruit Feather S3 TFT is the same basic thing, it too is a esp32-s3-devkitc-1 type of board BUT because they provided a board-specific definition to use in the IDE, all the config gets auto/properly set up so you dont have to hunt around or do anything else!
Bottom line: T-Display-S3 is pretty much useless in PlatformIO without LilyGo contributing an official board definition we can add to these IDEs.