In the Drupal administration section, each theme has its own settings page at admin/appearance/settings/themeName. This page has a form with standard settings like “Logo image settings” and “Shortcut icon settings.”
There are various ways you can add blocks to regions in pages in Drupal. You could add it in the block interface, use Panels or Context. But what if you just want to place a block directly in a Twig template?
The simplest way to place a block in a Twig template is to use the Twig Tweak module. Twig Tweak is a very handy module that gives you a range of functions to make theming with Twig easier.
Install Twig Tweak
This is how you can get the url of a field link rendered as a string (internal or external).
<a href="{{ node.field_link.get(0).getUrl().toString() }}">{{ node.field_link.get(0).title }}</a>