The toZonedDateTimeISO() method of Temporal.Instant instances returns a new Temporal.ZonedDateTime object representing this instant in the specified time zone using the ISO 8601 calendar system.
toZonedDateTimeISO(timeZone)timeZoneEither a string or a Temporal.ZonedDateTime instance representing the time zone to use. If a Temporal.ZonedDateTime instance, its time zone is used. If a string, it can be a named time zone identifier, an offset time zone identifier, or a date-time string containing a time zone identifier or an offset (see time zones and offsets for more information).
A new Temporal.ZonedDateTime object representing this instant in the specified time zone using the ISO 8601 calendar system.
RangeErrorThrown if the time zone name is invalid.
TypeErrorThrown if timeZone is not a string or a Temporal.ZonedDateTime instance.
const instant = Temporal.Instant.from("2021-08-01T12:34:56.123456789Z");
const zonedDateTime = instant.toZonedDateTimeISO("America/New_York");
console.log(zonedDateTime.toString()); // 2021-08-01T08:34:56.123456789-04:00[America/New_York]
const localDateTime = instant.toZonedDateTimeISO(Temporal.Now.timeZoneId());
console.log(localDateTime.toString()); // This instant in your timezone