[LibGDX] Screen scaling

Newbie & Debugging Questions
#1

So I started using libgdx for a while and I really really like it!
But what im missing in all of this, is the way of scaling things right!
My problem is:
-When i do a game, i do it to a default screen size, imagine 570x360, when i try to apply it, what im looking to do is resize whatever it takes so that way i would still work with the default screen size coordinates being 360 the max width and 570 max height, but i want to be able to resize whatever is on the screen to the current screen size, like drawing everything first into the 570x360 screen, but then rezise the screen.

I dont know if you are understanding what i want to do but heres an example what i used to do:

   //render image in the canvas, resizing acording to scale
   private void render() {
	BufferStrategy bufferStrategy = getBufferStrategy();
	if (bufferStrategy == null) {
		createBufferStrategy(3);
		return;
	}
	Graphics g = bufferStrategy.getDrawGraphics();
	draw((Graphics2D) image.getGraphics());
	g.drawImage(image, 0, 0, WIDTH * SCALE, HEIGHT * SCALE, null);
	g.dispose();
	bufferStrategy.show();

}

    //drawing stuff in the 570x360 BufferedImage
    public void draw(Graphics2D g) {
	g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
	g.setColor(getBackground());
	g.fillRect(0, 0, WIDTH, HEIGHT);
	stateManager.draw(g);
}

Please I really need some help on this one!

#2

If you are using an OrthographicCamera use the OrthographicCamera.setOrtho() method and give it your monitor size, then in your Main Class set the width and height of the LwjglApplicationConfiguration to the device screen size. That does the trick (for me at least). And for mouse/touch scaling you can use the OrthographicCamera.unproject() method that will transform the Vector3 that passed to a scaled version of itself.

#3

What im saying is first I wanna render all of my stuff int some sort of layer with the default screen size, the one that im using to program, and then strech it till it reaches the width and height that are expressed in the configuration.