@teastain2,
Thanks again for your help, and for confirming Arduino 2.1.1 was working fine with the LilyGo T-Display S3 on your system.
After spending virtually the whole day on this, I was able to pin-point the problem and work out a solution.
First, let me say I have also been using the ESP-IDF for some projects.
With that in mind, somewhere along the line I updated the CH430/431 driver to its most current version (3.8).
This turned out to have been at the root of the problem. Finding this post: https://github.com/espressif/esptool/issues/879 I tried reverting the driver to version 3.5, but that alone did not resolve the problem - although it was indeed the key part of the solution.
After downgrading the driver, the sketch would still not upload on either of the two LilyGo T-Display S3 boards which I was working with via the Arduino IDE 2.1.1.
However, I found that I could upload a very basic "hello world" like sketch to the LilyGo T-Display S3 using the ESP-IDF. Also, once I did this, I could then upload the sketch that I needed to the same board using the Arduino IDE.
In other words, it appears not only did the use of the current CH430/431 driver (3.8) prevent uploads to the LilyGo T-Display S3, it also somehow appears to have corrupted the flash in the board such that even with the right driver the Arduino IDE could not upload to it.
Using the ESP-IDF to upload to the board, seems to have reset things such that the Arduino IDE would again work fine with the 3.5 version of the CH430/431 driver.
I repeated the process with my second LilyGo T-Display S3 and got the exact same positive results.
Just posting this here in case it will be of use to others.
Thanks again to @teastain2 on this forum, and xamfa, radimkarnis. and mentesix on the Espressif forum for there help and posting toward this resolution.