Could you please elaborate a little bit on the use case?
As you state it you’d have an atomic note [[Elon Musk secrets]] and one on [[productivity]].
My immediate reflex would be:
Make an [[Elon Musk]] atomic note
Make a note [[Elon Musk - Secrets]] (with backlink to [[Elon Musk]]
Make a note [[Elon Musk - Productivity]] (with backlink to [[Elon Musk]]
Suppose the [[Secrets]] and [[Productivity]] become an atomic note later (not linked to Elon Musk alone) the links will automatically change when you rename the [[Elon Musk - Secrets]] to [[Secrets]] when you decide to split it off. Keeping the backlinks in the [[Secrets]] atomic note will still leave you the link to Elon Musk.