WP: Filter Content

remove_lazy_load_attr.php

<?php

function remove_lazy_load_attr( $content ) {

  // Condition
	if ( is_front_page() ) {

    // Objectify DOM
    $content  = mb_convert_encoding( $content, 'HTML-ENTITIES', 'UTF-8' );
    $document = new DOMDocument();
    
    libxml_use_internal_errors( true );
    
    $document->loadHTML( utf8_decode( $content ) );
    
    // Get first `img` tag
    $image = $document->getElementsByTagName( 'img' )[0];
    
    if ( is_object( $image ) ) {
    
      $image->removeAttribute( 'loading' );
      
      $content = $document->saveHTML();
    }
  }
  
  return $content;
}
add_filter( 'the_content', 'remove_lazy_load_attr' );

remove_lazy_load_attr_by_id.php

<?php

function remove_lazy_load_attr_by_id( $value, $image, $context ) {

  if ( 'the_content' === $context ) {
    
    $image_url = wp_get_attachment_image_url( 4532, 'large' ); // Attachment ID and size
    
    if ( false !== strpos( $image, ' src="' . $image_url . '"' ) ) {
    
      return false;
      
    }
  }
  return $value;
}
add_filter( 'wp_img_tag_add_loading_attr', 'remove_lazy_load_attr_by_id', 10, 3 );