These changes require to install a Divi child theme with a Blog module inside. Check the following article if you don't have a child theme with the Blog module in it yet:
Moving the blog module in child theme article

Next, open up includes/Blog.php file from the child theme folder and search for this code:

$args['cat'] = implode( ',', self::filter_include_categories( $include_categories ) );

$args['paged'] = $et_paged;

Add this code just below it:

$args['orderby'] = 'title';

$args['order'] = 'asc';

Save the changes.

This should show the posts of the blog module ordered by title in Ascending order.

If you want to change it to descending then in the previous code, change 'asc' to 'desc'.