macos – How do I assign the modifier fn to another key modifier (on the internal keyboard)?

Under Settings> Keyboard> Key modifiers I can re-assign (swap) all key modifiers (Command, Option, Ctrl) with the exception of Fn. In fact, for the function modifier, the only option I can map it to is the function key.

So how could I reassign the fn modifier to the ctrl key (on the internal kbd)?
Macbook Pro 10.15?