CFMAP Marker size

What are you expecting?  CFMap is just an interface to the Google Map API.  The markers there don't have any size property, see https://developers.google.com/maps/documentation/javascript/reference#MarkerOptions

Your best bet is you can specify different images to use, using the 'icon' attribute.  If you're using CFMap you can use the markericon attribute of the cfmapitem tag. See https://wikidocs.adobe.com/wiki/display/coldfusionen/cfmapitem

However I'd strongly recommend ditching cfmap completely and doing it all yourself directly via javascript and the Google Maps API directly.  For instance check this simple example here: https://developers.google.com/maps/documentation/javascript/markers#simple_icons