How can I locate my iPad without using Find My?

Other than using FindMy, there are no technical methods by which a lost or stolen iPad can be located.

Start here:

Locate a device in Find My on iPad - Apple Support

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. 

However, if the feature was not activated prior to being misplaced - or the iPad has been inactive or without a network connection 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.

Your iPad must have been set up in Find My in order to use Find My to locate it.

Add your iPad to Find My - Apple Support