Help with security and support for my iphone

See the following Apple Support article for information on adding security keys for your Apple ID: About Security Keys for Apple ID - Apple Support

Note that the security keys provide security for your Apple ID but otherwise don't increase protection for your iPhone.

Perhaps to outline and propose what might be the cause of your concern

may help to address this issue? I've several bookmarked pages in browser

some differ due to varying depth. ~ And as a Volunteer in ASC discussions

this is a matter of personal time & resources; of which mine are few.

If you think your Apple ID has been compromised - Apple Support

//support.apple.com/en-us/HT204145

Security and your Apple ID - Apple Support

//support.apple.com/en-us/HT201303

Keychains | Apple Developer Documentation

//developer.apple.com/documentation/security/keychain_services/keychains

Change your Apple ID security questions - Apple Support

//support.apple.com/en-us/HT201363

About Rapid Security Responses for iOS, iPadOS, and macOS - Apple Support

//support.apple.com/en-us/102657

About Security Keys for Apple ID - Apple Support

//support.apple.com/en-us/HT213154

[These are among others; please discover the nature you wish to explore.]