I need some help related to image sizing in Xamarin Farms Cross PlatForm.

I need some help related to image sizing in Xamarin Farms Cross PlatForm.
I have taken the picture from my mobile using the Plugin.Media. Its generate the image in my mobile with the size of 1.42 MB and Resolution 2160x2160. I need to upload this image using Rest API. First thing is this is it possible that this size decrease to kbs?

Second thing is this i use the Xamarin.Plugin.ImageEditer to change the image size to 768x1024. It change the image size but the size is still in 1MB. The code is as following.

private async Task<byte[]> ResizeImage(string ImagePath)
{

        FileStream fs = new FileStream(ImagePath, FileMode.Open, FileAccess.Read);

        using (var image = await CrossImageEdit.Current.CreateImageAsync(fs))
        {
            var imgReSiz = await Task.Run(() =>
                    image.Resize(768, 1024)
                         .ToPng()
            );
            return imgReSiz;


        }


    }

What i can do to set the image size not more then 100kb?