change scale

HTML

<script src="https://maps.googleapis.com/maps/api/js"></script>
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<div id="googleMap" style="width:500px;height:380px;"></div>

JavaScript

var myCenter = new google.maps.LatLng(51.508742, -0.120850);

function initialize() {
    var mapProp = {
        center: myCenter,
        zoom: 15,
        mapTypeId: google.maps.MapTypeId.TERRAIN
    };
    var map = new google.maps.Map(document.getElementById("googleMap"), mapProp);
    var marker = new google.maps.Marker({
       position: myCenter,
       map: map,
       icon: {
        path: fontawesome.markers.MAP_MARKER,
        scale: 0.5,
        strokeWeight: 0.2,
        strokeColor: '#9300D6', 
        strokeOpacity: 1,
        fillColor: '#D69112',
        fillOpacity: 1
        }
    });
    
    /*var marker = new google.maps.Marker({
        position: myCenter,
    });*/
    
    marker.setMap(map);
}

google.maps.event.addDomListener(window, 'load', initialize);