If I get an appointment in Outlook from someone in the office who sends it from iCloud/iPhone, the face of the appointment itself says it is for the correct day/time, but when I we open the attached ICS file so it will be added to Outlook, it shows an hour difference (later). All settings in iCloud regarding TZ and DST seem correct, unless I am missing something. iCloud is set to use Central Time / Winnipeg (where we are located). Outlook is set to use the correct calendar TZ and DST. All computers are set to the correct time and TZ and all are set to automatic DST. Their web calendars, as most all other web calendar systems, are fine. Apparently this has been known about for many years and neither party is really doing anything about it (Apple/Microsoft) All MS calendar software products do the same thing - Exchange, Outlook, Windows Calendar, etc. With our company, it is only iCloud appointments that come through an hour different. As a result, an appointment scheduled for noon will be on the calendar at 1 PM. For example, if you subscribe to an Internet calendar that does not include DST information, Outlook will treat the events as referencing standard time and move them ahead an hour if they occur when DST is in effect. If you receive an iCalendar that does not include time zone offsets in the ical, Outlook may place the appointment on your calendar using standard time, not current time. You need to use a time zone that does not observe DST. If your location does not observe DST, DO NOT choose a time zone that does then deselect the option to automatically update for daylight saving time. You need to use a time zone with the correct DST settings for your location. File, Options, Calendar, Time Zones (The settings should be identical and a change made in one location should reflect in the other.)

Verify the settings are also correct in Outlook.

You can open Date and Time in Windows 10 by right-clicking on the time in the notification tray and choosing Adjust Date/Time.

Verify all computers involved are set to the correct time, time zone and Daylight Saving Time settings in Windows' Date/Time settings.

Outlook for mac change time zone