How you access the Control Center on iPad depends on the version of iOS running on your device.
iPad Air 2 was originally released with iOS 8.1, and the current latest version of iOS available for the device is iPadOS 13.4.1 (iPadOS is a marketing rebranding of iOS running on iPad devices starting with iOS 13).
Currently, in theory you could be running any version of iOS from iOS 8.1 to iPadOS 13.4.1. To check the version of iOS installed on your iPad, go to Settings app → General → About and check for the item named Software Version to determine the current version of iOS running on your iPad Air 2.
Now to access Control Center on an iPad with:
iOS 11 or earlier, swipe up from the bottom edge of the device screen.
iOS 12 or later, swipe down from the top-right corner of your screen.
To learn more, you can refer to the relevant Apple Support document, Access and customize Control Center on your iPad
Once you are able to gain access to the Control Center, you can easily determine if the orientation lock is enabled and toggle it.