How to recover passwords from a dead iPad?

If you were using iCloud to sync passwords, try looking on the Passwords app on another device.

Or if you were maintaining timely backup of the device, you can restore a backup to a working device. Read this support article to discover how to restore your iPhone, iPad, or iPod touch from a backup --> Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

Your iPad uses an encrypted filesystem. Unless you are able to successfully power-on your iPad such that it is running normally - and you are able to enter your passcode - all locally stored data will remain encrypted and beyond reach/unrecoverable.

Your passcode unlocks the iPad's Secure Enclave (its security chip) within which the only copy of the encryption keys required to decrypt your data are stored. If you can't enter the passcode, the encryption keys are not released to the OS to decrypt your data.

If your iPad was synchronised with iCloud, all synchronised data will be saved to iCloud - and will be synchronised with a replacement iPad (or your other Apple devices). Only data that is not synchronised with iCloud will have been irreversibly lost.

If you value your data, it is essential that you always keep a backup - this being true for any computer system, not just your iPad. For Apple devices, keeping a backup is relatively painless; you can natively backup your data using iCloud (this process being entirely automatic) or using iTunes:

How to back up your iPhone, iPad, and iPod touch - Apple Support

With a backup, should disaster strike, you can easily restore your data from the backup:

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support