Should the tap area be visible to users?

I am looking to find what the best practice is for tap areas, or tap targets.

There is a lot of discussion as to what is the best size to have as a minimum tap area.

There is also a some documentation which seems a sensible rule here.

Whilst it is obvious to me that the above rules and best practice has a minimum tap area - my question is this...

Is there a need to have the minimum tap area represented as a visual? For example - if a button is meant to be a minimum of 44 points high, should the visual button be 44 points high? Or can the tap area be take the 44 points, and the button be smaller - providing that nothing is intruding on its space?

Thanks