If you suspect battery issues with a brand new iPad, if purchased from Apple, you might be best advised to make use of the 14-day unconditional return period - and have the iPad replaced with another new iPad. Upon expiry of the 14-day window, any replacement will be for a refurbished (not new) device.
Otherwise, you should seek immediate help directly from Apple Support. You’ll find the Contact Support link at top-right of this page. Alternatively, you can initiate a support case or contact using the Apple Support App:
https://apps.apple.com/gb/app/apple-support/id1130498044
Only if you are outside of the 14-day return window would I recommend expending time and effort in attempting to diagnose and resolve a battery-related issue.
I hope this guidance is helpful to you.