Before considering preparation for reuse, first consider moving data and settings to the new iPad…
These support pages should get you wife started with setup of her new iPad - and the methods of transferring existing data from old to new iPad:
Set up your iPhone, iPad or iPod touch – Apple Support
Transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support
Use Quick Start to transfer data to a new iPhone, iPad or iPod touch – Apple Support
If the donor iPad, from which you are transferring your data precedes iOS12.4, QuickStart will not be available.
“Transfer” is rather a misnomer. In reality, your data and setup is merely cloned to the new device. Nothing is moved or removed from the original device.
An alternative is to restore either an iCloud or iTunes backup to the new device:
How to back up your iPhone, iPad and iPod touch – Apple Support
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
When you are ready, the best procedure for preparing you old device for reuse can be found here:
What to do before you sell, give away or trade in your iPhone, iPad or iPod touch – Apple Support