Best way to change grid layout

you can try it with filter on that.
Put this to your child-theme functions.php
context blog goes with the context : index

add_filter('avf_post_slider_args', function($atts, $context){
  global $posts;
  if($context == 'index') {
    $atts['type']  = grid; 
    $atts['columns']  = 2;
  } 
  if($context == 'archive') {
    $atts['type']  = grid; 
    $atts['columns']  = 4;
  }
  if($context == 'tag') {
    $atts['type']  = grid; 
    $atts['columns']  = 5;
  }
  return $atts;
}, 10, 2);

shortversion if the column-count is the same:

add_filter('avf_post_slider_args', function($atts, $context){
	global $posts;
	if($context == 'index' || $context == 'archive' || $context == 'tag') { $atts['columns']  = 2;}
	return $atts;
}, 10, 2);

But I think you are on a good way, if you already found the places in the source code where it has to be changed.
f.e on index.php – some lines under your columns (count) you see that filter (line55) avf_post_slider_args

Now this is not general knowledge like css or jQuery which serves as a basis for something like this.
It is pure Enfold knowledge. Enfold has a lot of hooks and filters already built in.
So I look at the list of hooks and filters and try to find out what they are for.
btw.: the list is not complete – if you search the whole enfold folder for “do_action” you will find a lot of possibilities.

By the way, it is very helpful to create a small file in which you write down such snippets with the purpose they have and possibly with a link to the post that refers to the application.

2nd : the documentation is well done and is usually ignored as an aid.

3rd : Read, read, learn.
By not only following my questions here, but also reading through questions from other participants, I get a good coverage of problems that can arise using the Enfold theme. Every question that is asked here – could also be a question from my customers to me.
If you look at my postings from the beginning here, you’ll see that I wasn’t exactly the expert either. The trick is to question the answers as to why the solutions offered work.