NotificationCompat android - how to show only Large icon without small

Small icon is mandatory. If you don't set a large one you'll get your small icon bigger in the middle of the circle with the color of your choice (setColor).

If i were you i'd put that blank E on a transparent background for smallicon, and set a red color for the circle.

Based on the previous answer you can also hide the expended view too :

int smallIconId = AnghamiApp.getContext().getResources().getIdentifier("right_icon", "id", android.R.class.getPackage().getName());
            if (smallIconId != 0) {
                notification.contentView.setViewVisibility(smallIconId, View.INVISIBLE);
                notification.bigContentView.setViewVisibility(smallIconId, View.INVISIBLE);
            }

get the small icon id and then try to hide it

int smallIconId = ctx.getResources().getIdentifier("right_icon", "id", android.R.class.getPackage().getName());
if (smallIconId != 0) { 
    if (notification.contentView!=null)
        notification.contentView.setViewVisibility(smallIconId, View.INVISIBLE);
}

try looking at this post it will help too

i test the code on api 18,23 (samsung j1,galaxy S6) work fine