DOUBLE LAYER IMAGE USING CSS WORK AS WATERMARK

.overlayer {

  height: 100%;

  width: 100%;

background-repeat: repeat;

  position: relative;

}

.overlayer:after {

  content: " ";

  position: absolute;

  top: 0;

  left: 0;

  bottom: 0;

  width: 100%;

height: 100%;

background-size:cover;

  background-image: url(https://dev.feqjaafar.com/wp-content/uploads/2020/11/Oyen-Ramaix300.png);

background-repeat: repeat;

  background-color: rgba(255, 255, 255, 0.4);

  background-blend-mode: lighten;

opacity:80%

}

WORPDRESS AUTHOR IMAGE PHP

 <div class="author-image"><?php
$get_author_id = get_the_author_meta('ID');
$get_author_gravatar = get_avatar_url($get_author_id, array('size' => 300));
if(has_post_thumbnail()){
    the_post_thumbnail();
} else {
    echo '<img src="'.$get_author_gravatar.'" alt="'.get_the_title().'" />';
}
?></div>