I have used the below code to convert the string to the required format. But in the output seconds, microseconds are missing.
LocalDate date = LocalDat.parse(inputString, DateTimeFormatter.ISO_LOCAL_DATE);
date.atStartOfDay(ZooneId.of("America/New_York").toOffsetDateTime().toString();
Output based on the above code: '2021-01-13T00:00-4:00'
Required output: '2020-01-13T00:00:00.000-4:00'