Placeholder text/icon in date picker field

Does anyone know how to add placeholder text or a calendar icon into a date picker field - it looks a bit odd to have just an empty field which doesn’t give any indication that a date picker will open if the field is clicked. Here are some examples of what I mean:

Screenshot 2020-05-25 at 17.30.57

Screenshot 2020-05-25 at 17.30.35

Alternatively, is there a way to add a clickable image/icon that will activate the date picker when clicked, as in the second example above.