With the release of the Holiday Season update, Thai language is now supported in Gran Turismo Sport. If you are currently playing in another language and want to switch to Thai, please perform the following steps (please note this applies only to players who are not playing for the first time after the Holiday Season update):
1: From the Top Screen, go to [GT Menu] -> [Options] -> [Language];
2: Turn [Re-select Language] to [On], then go back to the Top Screen, and restart the game;
3: When the game restarts, you will be presented with a language selection Menu;
4. Select Thai.
You are now able to play 'Gran Turismo Sport' in the Thai language.