Hi Nbaunn,
welcome to the Apple (user-to-user) Community!
Re: Why can't I send messages to Apple Support from my iPhone
We can't guess which of many possible reasons from the info. supplied.
✽ Are you using the newest compatible iOS version on your iPhone ? : About iOS 17 Updates - Apple Support
or
✽ Sometimes just restarting your iPhone restores order when something is not working as expected:
(Eg: Deletes temporary files, re-establishes connections, may update recent setting changes, and more)
If needed: How to: Restart your iPhone - Apple Support
✽ You can always check the System Status page to see if there are any outages: Apple - Support - System Status
Else:
✽ You might want to try using the "Support" link at top right, or the one at bottom left, on this discussion page.
✽ Other options: Support webpage: Official Apple Support
or
✽ See a list of Apple phone numbers around the world to: Contact Apple for support and service - Apple Support
All the best :-)