ORDS, SODA & JSON in the Database

i am trying to use this function to get the date which json supports ,
[code]
SELECT TO_UTC_TIMESTAMP_TZ('01-JAN-2021') FROM DUAL;
[/code]

i am getting the ORA-00904 as invalid identifier. how do i specify the dates in zulu format. couple of ways i tried in payload , but how to tell the consuming service people which format to use.