Three basic troubleshooting steps to perform (test after each attempt):
A) I suggest that you put it on charge for at least half an hour, then, keeping it plugged in, try a "forced" restart of your iPad, using these instructions:
- On an iPad with a Home button: Press and hold the power button and the Home button at the same time. When the Apple logo appears, release both buttons.
- On other iPad models: In rapid sequence, press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the power button. Only when the Apple logo appears (it might take 10-20 seconds), release that button (ignore all other screens that might appear, the one with the "slider" to turn the device off included).
B) Check your device's internal storage in Settings>General>IPad Storage. You should have, at least 5-10GB free.
Shouldn't be this case, try to make room by deleting unused stuff.
C) If the issue persists, something could have gone wrong during the latest update procedure.
I would try to install a fresh copy of iOS/iPadOS (the latest available/supported by your device model). To do this, create a full backup of your iPhone/iPad (1), then restore it to factory settings (you need a computer to perform this step) and, in the end, set it up as new (2).
When done, restore data from your previously made backup (3).
Follow the instructions provided in these support articles:
(1) How to back up your iPhone, iPad, and iPod touch – Apple Support
(2) Restore your iPhone, iPad, or iPod to factory settings – Apple Support
(3) Restore your iPhone, iPad, or iPod touch from a backup
If the issue still persists, it could be a hardware (battery? other internal component?) failure but we, just users like you, cannot diagnose those issues remotely. I recommend that you make an appointment (*) and have your device inspected at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> https://locate.apple.com/choose-country-region . After checking it out, they'll give you all the available options.
Regards
Giulio
(*) You can do it: