Add this code to the Custom CSS field on the Appearance tab of your Google Maps widget’s settings:
.eapps-google-maps-marker-title {
font-size: 20px;
}
.eapps-google-maps-marker-content {
font-size: 16px;
}
.eapps-google-maps-marker-directions {
flex-shrink: 0 !important;
}