Password protecting the wp-content maybe not a good idea because then theme will unable to display all images. If you want the images are not displayed in google search Create a Robot.txt file in your root directory in hosting and add the code below.

   User-agent: *
   Disallow: /wp-admin/
   Disallow: /wp-includes/
   
  or below if you want to not specific images 

   User-agent: Googlebot-Image
   Disallow: /images/yourImageName.jpg #yourImageName.jpg image for Googlebot 
   specifically.

1. Use this plugin and add below code in Settings>Phpinserter

   add_action( 'wp_head', function() { if ( is_page( 'your_page_name' ) ) { echo ''; } } ); your specific page will be not index by Google

Or you can pick plugin of your choice from here. It is a preferable method but you have to find some free plugins for content restriction.

Some plugins for restriciting page contents

Password protecting the wp-content maybe not a good idea and may break your site interface. If you want the images are not displayed in google search Create a Robot.txt file in your root directory in hosting and add the code below.

   User-agent: *
   Disallow: /wp-admin/
   Disallow: /wp-content/
   
  or below if you want to not specific images 

   User-agent: Googlebot-Image
   Disallow: /images/yourImageName.jpg #yourImageName.jpg image for Googlebot 
   specifically.

1. Or Use this plugin and add below code in Settings>Phpinserter

Blockquote

add_action( 'wp_head', function() {
if ( is_page( 'your_page_name' ) ) {
    echo '<meta name="robots" content="noindex">';
}} );

your specific page will be not index by Google

Or you can pick plugin of your choice from here. It is a preferable method but you have to find some free plugins for content restriction.

Some plugins for restriciting page contents