Make all shop items description boxes the same size

Try this code:

add_filter('the_title', 'modify_title', 10);
function modify_title( $title ) {
  if ( is_woocommerce() || is_product_category() ) {
    if ( strlen( $title ) > 12 ) {      
      $title = substr($title, 0, 12).'...';
    }
  }
  return $title;
}

The ’12’ is the maximum number of characters you want to allow. Adjust the number to your preference.

The code goes in functions.php for your child theme or you could use the “My Custom Functions” plugin or similar.

OK. You can get some regularity by specifying a minimum height for the title block with this custom css:

.woocommerce-loop-product__title {
  min-height: 46px;
}

Custom css can be entered at Appearance > Customize > Additional CSS

However, your images have different aspect ratios, so they will show the same width but their heights will be different. Its possible to force the image heights to be the same but then there will be some distortion.