For what its worth, I could not get this to work under Arduino IDE 2.3.2
I tried the above suggestions but always got errors. <process.h> not found (tried it with "process.h") was the main one that caused me to think "stuff this" so I fired up a new install of VS Code, install extensions for Platform IO and Python, let it do its thing for setup. Selected Lily T-Display S3 on COM3, a couple of other things needed to be configured that it asked me to do. Then I pointed it to the Examples Factory folder ... it farted about for a bit installing libraries but that was it ... nothing else needed to be done. It had a couple of errors in first build but they were resolved with a second build and it uploads so very much quicker than Arduino IDE.