When Time Zone Support is on, Calendar displays event dates and times in the time zone of the city you selected.
When Time Zone Support is off, Calendar displays events in the time zone of your current location as determined by your Internet connection. When you travel, iPad may not display events or sound alerts at the correct local time.
To manually set the correct Date & Time
These settings apply to the time shown in the status bar at the top of the screen, and in world clocks and calendars.
Set whether iPad shows 24-hour time or 12-hour time: Go to Settings > General > Date & Time. (24-Hour Time may not be available in all countries or regions.)
Set whether iPad updates the date and time automatically
Go to Settings > General > Date & Time.
If iPad is set to update the time automatically, it determines your time zone based on your Internet connection and updates it for the time zone you’re in. If you’re traveling, iPad may not be able to automatically set the local time.
Set the date and time manually
Go to Settings > General > Date & Time, then turn Set Automatically off. Tap Time Zone to set your time zone.