Does iOS 16 work on the 9th generation iPad?

No, iOS doesn't work on any iPad. iOS is only for iPhones.

iPad OS 16 will be released today, though. It is compatible with these iPads:

• iPad Pro (all models)
• iPad Air (3rd generation and later)
• iPad (5th generation and later)
• iPad mini (5th generation and later)

The 9th generation iPad is only 1 year old so it should work.

Yes and no. Upon release later today, your iPad9 can be updated to iPadOS16.x.

The currently available iOS 16.0.3 for iPhone cannot be installed on any iPad.