"Battery health" is influenced by many factors.
An iPad battery is nominally rated to retain 80% of its original capacity (when new) after 1000 full recharge cycles. Any combination of charging that together sums to 100% equates to one full charge cycle (e.g., 50% + 20% + 20% + 10% = 100% = 1 full charge cycle). As such, reducing the number of times that the iPad is recharged will slow the rate that the iPad's battery health will decline due to recharging.
Other factors can influence overall battery health. High ambient temperatures can permanently reduce the battery's ability to retain full charge - as can maintaining the battery at 100% charge for very long periods of time that leads to chemical aging of the battery. Limiting the battery charge to ~80% of maximum is intended to reduce the chemical aging effect.
Information about iPad’s battery management can be found here:
About iPad and iPhone Charge Management Feature – Apple Support
If you have any concerns for your iPad or its Battery Health you would be well advised to seek assistance directly from Apple Support - and request a remote diagnostic test of your iPad. You can contact the Support Team using the Support link at top-right or bottom-left of this page.
Alternatively, you can initiate and manage your support cases from Apple devices using the excellent Apple Support App. If not already installed, the App can be downloaded from the App Store:
https://apps.apple.com/app/apple-support/id1130498044
You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to hands-on test and assess your iPad. If an issue is identified, you'll be in the best possible place to explore your available options:
Genius Bar Reservation and Apple Support Options - Apple
