Editing only one field in a post

Part, I am trying to configure the form in such a way that it only edits one field in the post. However, it creates a new post every time and does not rewrite values that have already been completed.

I use the hook for this:
add_filter (‘cf7_2_post_filter_user_draft_form_query’, ‘custom_post_query’, 10.2);
function custom_post_query ($ query_args, $ post_type) {
if (‘my-mapped-post’ === $ post_type) {// check for your mapped post type.
// set up your custom $ query_args
}
return $ query_args;
}

I enter the hook in the additional settings tab. I don’t know if this is the correct place;)