If the iPad is Activation Locked, you’ll need the AppleID and Password that was previously used to activate the iPad.
Assuming that you have full access to the iPad - and know the necessary AppleID Password, you can remove the Activation Lock relatively easily:
Settings > [Name / AppleID] > Find My > Find My iPad > Find My iPad - set to OFF; you’ll be challenged for the AppleID Password
If you are attempting to properly prepare the iPad for reuse, the most effective method is to follow this procedure:
What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support
This process will completely erase the iPad, remove the Activation Lock and reset - after which you’ll be able to set-up afresh as a new iPad.
If you have transferred data and settings from old to new iPad using QuickStart, or restored from a Backup associated with the previous iPad, you will have literally transferred everything from old to new - and will have an iPad that is effectively not yours. Starting again from scratch is recommended.