KilukruMedia

Simply add anchors links inside your content. Shortcode <code>[wpanchor id="your_id"]</code> is added via a button in Wisiwig. After your need to create a link inside your site with #your_id for the href link. Your link look likes <code><a href="#your_id">my link</a></code>

WP Simple Anchors Links

Insert simply many anchors to pages, posts and custom post type.

gonafr

Check content and create a widget menu with links that point to words between the HTML tags you choose. 
It was initially thought and created for the HTML tags of the titles (h1, h2, h3…), but you can use it in other situations.

Anchors Menu

Check content and create a widget menu with links that point to words between the HTML tags you choose.

WP Simple Anchors Links vs Anchors Menu