This will create a larger notification InBoxStyle Notification

MainActivity.java

private void createInboxStyleNotification() {
        NotificationCompat.Builder mBuilder =
                new NotificationCompat.Builder(this)
                        .setSmallIcon(R.mipmap.ic_launcher)
                        .setContentTitle("My notification")
                        .setContentText("Hello World!");
        NotificationCompat.InboxStyle inboxStyle =
                new NotificationCompat.InboxStyle();
        String[] events = new String[6];
        events[0] = "Line 1";
        events[1] = "Line 2";
        events[2] = "Line 3";
        events[3] = "Line 4";
        events[4] = "Line 5";
        events[5] = "Line 6";
        // Sets a title for the Inbox in expanded layout
        inboxStyle.setBigContentTitle("Event tracker details:");
        // Moves events into the expanded layout
        for (String event : events) {

            inboxStyle.addLine(event);
        }
        // Moves the expanded layout object into the notification object.
        mBuilder.setStyle(inboxStyle);
        Intent resultIntent = new Intent(this, MainActivity.class);

        // The stack builder object will contain an artificial back stack for the
        // started Activity.
        // This ensures that navigating backward from the Activity leads out of
        // your application to the Home screen.
        TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
        // Adds the back stack for the Intent (but not the Intent itself)
        stackBuilder.addParentStack(MainActivity.class);
        // Adds the Intent that starts the Activity to the top of the stack
        stackBuilder.addNextIntent(resultIntent);
        PendingIntent resultPendingIntent =
                stackBuilder.getPendingIntent(
                        0,
                        PendingIntent.FLAG_UPDATE_CURRENT
                );
        mBuilder.setAutoCancel(true);
        mBuilder.setContentIntent(resultPendingIntent);
        NotificationManager mNotificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        // mId allows you to update the notification later on.
        mNotificationManager.notify(101, mBuilder.build());
    }