How to import contact from another child account without disabling Lockdown Mode in iOS 18.5?

Thanks but I am quoting following advise from Apple website which I thought helps scam risk ( news around here recommending scam risk apps); Another reason is performance (media IMHO slows down my not-latest-model of iOS device). I would think Lockdown mode mitigate my concerns.

• “Messages - Most message attachment types are blocked, other than certain images, video, and audio. Some features, such as links and link previews, are unavailable. 
• Web browsing - Certain complex web technologies are blocked, which might cause some websites to load more slowly or not operate correctly. In addition, web fonts might not be displayed, and images might be replaced with a missing image icon.

I think you should go back and read what lockdown mode is actually for...

About Lockdown Mode - Apple Support

"Lockdown Mode is an optional, extreme protection that’s designed for the very few individuals who, because of who they are or what they do, might be personally targeted by some of the most sophisticated digital threats. Most people are never targeted by attacks of this nature."

Why do you think you need to use lockdown mode?

Lockdown mode is for those at extreme risk from sophisticated attacks by entities like repressive governments.