ipad A1584 - battery replacement

You can establish eligibility and cost of a battery replacement for your iPad in your country/region here:

iPad Repair & Service - Apple Support

For practical purposes, Apple often exchange a qualifying iPad for a renewed/refurbished iPad of the same model and specification. The cost of the exchange is the same as would otherwise be charged for the replacement battery alone.

I have the same iPad Pro modrl as you.

This iPad year amd model is, now, categorised, as “Vintage”, by Apple.

It maybe too old, now, for Apple to offer a replacement device for a battery replacement service and many Apple Store locations DO NOT actually repair iPads or do actual battery replacement service on iPads.

So, getting the battery replaced in this almost 8-year old iPad model may no longer be possible.

Best of Luck to You!