My ipad 9th gen won’t update to 16 ios it keeps saying ipad ios 15.7 is up to date what should i do

Unlike iOS16 for iPhone, released 12th September, iPadOS16 is not due for release until sometime in October. 

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

While iOS16 is 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

Nothing.

it’s iPHONE iOS16 that was released this week. IPADOS16 will come out in October and then you can update

so you’re fine for the time being.