You may have already have followed the appropriate process, but in case anything may have been missed, 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 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. Remote management requires that the target device has an active network connection - as without it, commands cannot be received or executed by the target device.
Assuming that the devices are locked with Passcode that is unknown to anyone else, the devices will remain locked and inaccessible to others.