How to check battery health on IOS 16.1?

Unlike iPhone, iOS/iPadOS for iPad has never had the Battery Health feature - most likely because iPad batteries are both considerably larger and have a much longer service life.  An iPad battery is rated to maintain at least 80% of its initial capacity after 1000 full charge/discharge cycles - whereas an iPhone is rated to have 80% of initial capacity after 500 full cycles.

There are third-party software packages available that can access battery cycle count. Popular choices for Mac are Coconut Battery and iMazing - whereas iMazing is available for PC.

https://www.coconut-flavour.com/coconutbattery/

If you are experiencing difficulties with your iPad battery holding charge, you might be best advised to have your iPad tested.  If you directly contact Apple Support, you can request a remote battery diagnostic. The tests will confirm the status of your battery - and other elements of your iPad’s health.

Alternatively, a visit to the Genius Bar at your local Apple Store would provide opportunity for your iPad to be similarly tested by the Apple technicians.

When necessary, you can contact Apple Support using the Contact Support link at top-right of this page. You can also initiate a support case using the excellent Apple Support App; if not already installed on your iPad, the App can be downloaded from the App Store:

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

iPads and iPadOS do not have the battery health feature.

This is an iPhone ONLY feature.

iPads do not really need the Battery health app as iPad batteries are so much larger and powerful than iPhone batteries and last for a much longer period of time.

iPad batteries can last anywhere from 3 to 7-8 years, or even a bit longer, before an iPad may need a battery replacement.

If you still wish to monitor youf iPad battery health, anyways, and you own a fairly recent Mac, look online for a Mac battery app called Coconut battery.

https://www.coconut-flavour.com/coconutbattery/

Best of Luck to You!