Dynamically Change Number of Columns in Post Slider

The problem with this is that enfold groups the articles according to this column setting – meaning 3 columns will result in 3 articles in a slide-entry-wrap.
Maybe the developers could think about this behavior – because it hinders exactly this layout possibility you want to achieve.

The grouping then had to be done by flex layout

we can have a script to reach that layout – but better would be to get it on DOM generation.

( this is now only done here in my example snippet for one page ( my blog page only ID: 36400 )

function wrap_articles_in_one_flex_container(){ 
if(is_page(36400)){
?>
<script type="text/javascript">
window.addEventListener("DOMContentLoaded", function () { 
  (function($) {
    $('.avia-content-slider-inner .slide-entry-wrap .slide-entry').each( function() {
        $(this).detach().appendTo('.avia-content-slider-inner .slide-entry-wrap:first');
    });
    $('.avia-content-slider-inner .slide-entry-wrap:empty').remove();
  })(jQuery);
});
</script>
<?php
}
}
add_action('wp_footer', 'wrap_articles_in_one_flex_container');

and for css:

#top.page-id-36400 .avia-content-slider .slide-entry-wrap {
  display: flex;
  flex-flow: row wrap;
  justify-content: center;
}

#top.page-id-36400 .avia-content-slider .slide-entry-wrap .slide-entry {
  flex: 0 1 calc(25% - 30px);
  margin: 0 15px 30px;
  width: unset !important;
}

@media only screen and (max-width:1310px) {
  #top.page-id-36400 .avia-content-slider .slide-entry-wrap .slide-entry {
    flex: 0 1 calc(33% - 30px);
    margin: 0 15px 30px;
  }
}

@media only screen and (max-width:989px) {
  #top.page-id-36400 .avia-content-slider .slide-entry-wrap .slide-entry {
    flex: 0 1 calc(50% - 30px);
    margin: 0 15px 30px;
  }
}

@media only screen and (max-width:767px) {
  #top.page-id-36400 .avia-content-slider .slide-entry-wrap .slide-entry {
    flex: 0 1 100%;
    margin-bottom: 30px !important;
  }
}

adopt to your blog ID
see here: https://webers-testseite.de/blog/