resize full width slider

From my point of view the other way would be easier to go. To make a full-screen slider look like a full-width slider.
Only the following problem is: Your pictures are not all in the same aspect ratio, that they do not have the same size (meant are the dimensions) is not relevant.

If you were to use the 1500px x 630px aspect ratio, for example, you could specify the following with this aspect ratio:
630/1500 = 42% – if we now take the screenwidth as basis we had 42vw as height

So make yourself a copy of your homepage which has only the fullscreen slider and shows it on all screen widths.
It would be nice if the images would have the same aspect ratio. So test the 1500px x 630px variant in the slider.
Then we convert the code only for this Page-id:
So e.g:

@media only screen and (max-width:767px) {
	.page-id-xyz .avia-slideshow.av_fullscreen {
	    width: 100vw !important;
	    height: 42vw !important;
	}
}

on a 16:9 aspect ratio it is 54vw height
on 801:1200 = 67vw
etc.

this is my function for him sofar- maybe a mod could tell me how to use the included debounce resize function on enfold for it:
( the selector has to be more specific – maybe an ID or Custom Class – but that could be done later)

function slider_move(){
?>
<script>
(function($){
	var fullscreenSlider = $(".avia-fullscreen-slider");
	fullscreenSlider.clone().detach();

	$(window).on('load resize', function () {		
		var winWidth = $(window).width();
		if (winWidth < 990) {
			$("#main").prepend(fullscreenSlider);
		}
		else {
			$("#wrap_all").prepend(fullscreenSlider);
		}
	});
})(jQuery);
</script>
<?php
}
add_action('wp_footer', 'slider_move');

If you don’t make yourself a slave to Performance Test Tools, then I think a little movement on the start page is good.
On my site I even have a small self-hosted movie running, which also works on the mobile phone!

Yes – but your biggest problem is the image optimization.
You can see on the F-Result for a lot of images that an optimized version is sometimes more than 40% reduction.
By the way – alot of beginners – download this presented optimized Version and upload them instead of the original.
One of the images is nearly 600kb big. thats immense for a web graphic

All you need to test is described on that page: https://webers-testseite.de/slider-depending-on-screenwidth/