Fictional Google Calendar practice answer
Thursday, January 21, 2027, 11:00–11:30 AM in New York is the same instant as 8:00–8:30 AM in Los Angeles and 16:00–16:30 UTC.
The .ics file encodes 20270121T160000Z to 20270121T163000Z. It is an expected-value fixture, not proof of what a recipient sees.
If the event displays one hour off, check the event date, selected city/time zone, and whether the calendar is showing its own primary zone.