How do I change the time on my iPad?

Your iPad will automatically set time using an external [NTP] Time Server. You can set the timezone - and the displayed time will show the correct time for where you are. Allowing the iPad to automatically set time is recommended - as many services will not operate correctly (if at all) if the displayed time substantially differs from the correct time.

The iPad User Guide describes how to alter the time settings on your iPad:

Change the date and time on iPad - Apple Support