updating watch to OS9

Do you have iOS16.3 on your iphone?

If you do then ensure you don't have VPN or app store security apps on the phone

see also

Apple Watch will not update. 

Try the steps here to troubleshoot not being able to update: Update your Apple Watch - Apple Support 

Need more help with updating? 

Try these steps: 

Make sure that your Apple Watch is connecting properly to its charger.  

If your Apple Watch won't charge or won't turn on – Apple Support (UK)

Restart your Apple Watch. Restart your Apple Watch – Apple Support (UK)

Restart your paired iPhone. Restart your iPhone – Apple Support (UK)

Try again to update your Apple Watch. 

If the update won't start: 

Open the Apple Watch app on your iPhone. 

Tap General > Software Update. 

Delete the update file. 

Try again to update your Apple Watch. 

Learn what to do if you see 'Cannot Install Update' when updating Apple Watch If you don’t have enough space to update your Apple Watch – Apple Support (UK) 

or if your Apple Watch says “you need more available storage to install a watchOS update.”  If you don’t have enough space to update your Apple Watch – Apple Support (UK) 

Thanks for letting us know what you tried. You have done all the troubleshooting that I know about.

And you have definitely checked the iphone profiles for anything at all even adblocker? (Check Settings, General, VPN & Device Management) 

If so then You ought to reach out to Apple Support directly. You should be able to reach them here  

Click here > Contact - Official Apple Support  

or phone numbers  

Click here > https://support.apple.com/en-us/HT201232