Unlike iOS16 for iPhone, released 12th September (iOS 16.0.1 subsequently released 16th September), iPadOS16 is not due for release until sometime in October. For reasons known only to Apple, release dates for iOS for iPhone and iPadOS for iPad have been deliberately staggered.
However, iPadOS 15.7 was also released 12th September - incorporating essential security updates.
About the security content of iOS 15.7 and iPadOS 15.7 - Apple Support
When iPadOS16 is released (anticipated October), it will be available for these models of iPad:
- iPad Pro (all models)
- iPad Air (3rd generation and later)
- iPad (5th generation and later)
- iPad mini (5th generation and later)
While iOS16 is currently available for iPhone, iPhone owners have the option to just install iOS15.7 at this time.
More information about the forthcoming iPadOS16 can be found here:
iPadOS 16 Preview - Apple
You should note that Apple’s published information clearly indicates the devices that are eligible for update. The security updates page also refers:
Apple security updates - Apple Support