My Ipad Air II does not hold a charge even when plugged in. Can this be fixed?

The iPad Air 2 is going on 7-years old.

It is possible that the internal, rechargeable battery maybe failing in that iPad.

Search online to locate and call contact your nearest, “local” Apple Store location to try/attempt to make an appointment to get your Apple iPad diagnosed and given possible options.

OR, failing that,

Contact Apple support via the contact support link located at the upper right hand corner of every Webpage of these Apple support communities OR by installing and using the Apple Support app found in the iOS App Store.

Tap the iOS App Store link below.

https://apps.apple.com/us/app/apple-support/id1130498044

Best of Luck to You!