Thème child

It should be possible with the Create Block Theme plugin.

I already have a child theme, the problem is when I activate it I no longer have the content of my parent site.
Thanks

The site content is not contained in the theme, so activating a different theme will not make the content unavailable.

I read your original question as asking how to create a child theme, so I think I have misunderstood your question.
Could you please provide more information about what you are trying to do?

Sorry I explained myself badly, I created a site with Twenty Twenty-Three, once the site was finished I needed an option, on the forum I was given a code to add to the function.php page, for update reason it is better to install a child theme, which i did, when i activate the child theme everything i did on the parent theme does not appear on the theme child, I have to disable the child theme to find my site, I guess there are files to transfer from one theme to another.
I found in the options the export but not the import.

If you just want to add some php code, it might be worth trying a plugin such as Code Snippets.

This will let you add custom code without needing to add it to the theme’s functions.php file.

Ok thanks, I’ll try that.