customize the height and width of ESRI map callout - xamarin.forms

Question

here is the formatted String which i am binding to callout but i am able to see only some contents of my string in callout
private async void WebMapView_GeoViewTapped(object sender, GeoViewInputEventArgs e)
{
try
{
WebMapView.DismissCallout();
MapPoint mapLocation = null;
var layers = await WebMapView.IdentifyLayersAsync(e.Position, 20, false);
if (layers.Count > 0)
{
foreach (var idResults in layers)
{
FeatureLayer idLayer = idResults.LayerContent as FeatureLayer;
await idLayer.LoadAsync();
var result = layers.First();
var feature = result.GeoElements.First() as ArcGISFeature;
await feature.LoadAsync(); // Load feature to get all attributes
Feature idFeature = result.GeoElements.First() as Feature;
featureAttrs = idFeature.Attributes;
var stateExtent = idFeature.Geometry;
Graphicoverlay = new GraphicsOverlay();
Graphic graphicLine = null;
graphicLine = new Graphic(stateExtent, AppConstant.HighLight1);
Graphicoverlay.Graphics.Add(graphicLine);
EnvelopeBuilder myEnvelopeBuilder = new EnvelopeBuilder(SpatialReferences.WebMercator);
//Geometry abd = oneGraphic.Geometry;
myEnvelopeBuilder.UnionOf(graphicLine.Geometry.Extent);
myEnvelopeBuilder.Expand(1.3);
mapLocation = myEnvelopeBuilder.Center;
Geometry myGeometry = GeometryEngine.Project(mapLocation, SpatialReferences.WebMercator);
MapPoint projectedLocation = (MapPoint)myGeometry;
string formattedString = "";
if (featureAttrs.Count > 0)
{
foreach (var attributes in featureAttrs)
{
string recordOneAttribute = $"{attributes.Key} {attributes.Value}";
formattedString = $"{formattedString}\n{ recordOneAttribute}";
}
}
CalloutDefinition calloutDef = new CalloutDefinition("Feature:",formattedString);
WebMapView.ShowCalloutAt(mapLocation, calloutDef);
}
}