Tell us what you are trying to do
Make a child post added via the parent editor (see attached) when saved not to be published automatically, but instead can we make it as draft or publish after 72 hours.
Is there any documentation that you are following?
Just the one to many relationship set-up
There aren't any settings, nor a Toolset API hook where you could intervene in adding a related post through the normal back-end post edit screens to make new related posts have a draft or pending status.
To change the status you would need to use the WP API itself, e.g. the save_post hook (or, better, the CPT version of that hook), to trigger a script where you could check if you were on the post edit screen for the parent post (via get_current_screen) and if so change the status (or push the publish date forward) for the child post.