Changing the initial offset value with ACF custom field

ba_img_initial_offset.php

<?php //* do not include this line if you are adding into the functions.php file
/**
* Write the code in snippets plugin
*/

add_filter( 'before_after_image_initial_offset', 'ou_change_before_after_image_initial_offset');
function ou_change_before_after_image_initial_offset( $offset ) {
  global $post;
  
  if( ! is_a( $post, 'WP_Post') )
    return $offset;
  
  //* fetching the custom field data
  $offset_value = get_post_meta( $post->ID, 'ENTER CUSTOM FIELD KEY', true );
  
  if( ! empty( $offset_value ) )
    return $offset_value;
  
  return $offset;
}