Render link elements in blocks?
You have to build a render array like this:

   public function build() {
     $build = [];
     $build['linkA'] = [
       '#type' =&gt; 'link',
       '#title' =&gt; 'Link A',
       '#attributes' =&gt; [
         'class' =&gt; 'link-class',
         'target' =&gt; '_blank',
       ],
       '#url' =&gt; Url::fromUri($this-&gt;configuration['default_LinkA_url']),
     ];
     $build['linkB'] = [
       // ...
     ];

     return $build;
   }


You can add attributes to the link, classes for css or a target to open it in a new tab.