How can I determine my iPad last location if it is offline?

Here is Apple’s advice for lost or stolen devices:

If your iPhone, iPad or iPod touch is lost or stolen – Apple Support

Use the Find My app to locate a lost or stolen device – Apple Support

If the Find My iPad feature was enabled prior to it being “misplaced”, then if active, you would stand a good chance of locating it - providing that the device has an active network connection.

However, if the feature was not activated prior to being misplaced - or the iPad has been inactive for more than 24 hours - the last known location will not be available and the opportunity to use technical means to recover the iPad have been lost.

It must be turned on and online in order to send a signal. Otherwise you must search the old-fashioned way.