Post the page content in template via page id or slug

post_page_content.php

$pageID = 'page name or slug';
get_ID_by_slug($pageID );


// page id by slug
function get_ID_by_slug($page_slug) {
    $page = get_page_by_path($page_slug);
    if ($page) {
        return $page->ID;
    } else {
        return null;
    }
};

// Post Page Content
function post_page_content($page_slug) {
  get_ID_by_slug($page_slug );
	
	$id = get_ID_by_slug($page_slug );
	$post = get_page($id); 
	$content = apply_filters('the_content', $post->post_content); 
	return $content; 
}