trim auto and manually excerpts

Displaying the manual and auto excerpt the same way with [...] at the
end and Bootstrap .btn-default „read more“ link below

content.php

@@ -21,14 +21,11 @@
     <?php echo get_the_post_thumbnail( $post_id, 'large' ); ?> 
     
 	<div class="entry-content">
-        
-		<?php
-			/* translators: %s: Name of current post */
-			the_excerpt( sprintf(
-				__( 'Continue reading %s <span class="meta-nav">&rarr;</span>', 'understrap' ),
-				the_title( '<span class="screen-reader-text">"', '"</span>', false )
-			) );
-		?>
+
+            <?php
+                /* translators: %s: Name of current post */
+                the_excerpt( );
+            ?>
 
 		<?php
 			wp_link_pages( array(

inc/setup.php

@@ -85,10 +85,21 @@ add_filter('show_admin_bar', '__return_false');
 /**
 /* Adding the Read more link to excerpts
 */
-function new_excerpt_more( $more ) {
+/*function new_excerpt_more( $more ) {
 	return ' <p><a class="read-more btn btn-default" href="'. get_permalink( get_the_ID() ) . '">' . __('Read More', 'understrap') . '</a></p>';
 }
-add_filter( 'excerpt_more', 'new_excerpt_more' );
+add_filter( 'excerpt_more', 'new_excerpt_more' );*/
+/* Removes the ... from the excerpt read more link */
+function custom_excerpt_more( $more ) {
+	return '';
+}
+add_filter( 'excerpt_more', 'custom_excerpt_more' );
 
-/* Add support for Featured Images per Post */
+/* Adds a custom read more link to all excerpts, manually or automatically generated */
 add_theme_support( 'post-thumbnails' );
+
+function all_excerpts_get_more_link($post_excerpt) {
+
+    return $post_excerpt . ' [...]<p><a class="btn btn-default" href="'. get_permalink($post->ID) . '">' . 'Read More...' . '</a></p>';
+}
+add_filter('wp_trim_excerpt', 'all_excerpts_get_more_link');

index.php

@@ -28,6 +28,7 @@ get_header(); ?>
                     <?php /* Start the Loop */ ?>
                     
                     <?php while ( have_posts() ) : the_post(); ?>
+
                         <?php
                             /* Include the Post-Format-specific template for the content.
                              * If you want to override this in a child theme, then include a file
@@ -35,6 +36,7 @@ get_header(); ?>
                              */
                             get_template_part( 'content', get_post_format() );
                         ?>
+
                     <?php endwhile; ?>
                     
                     <?php understrap_paging_nav(); ?>