Snippet to dynamically add the year or a custom dynamic date to your page.html.twig file. In your mytheme.theme file, first add:
/**
* Implements hook_preprocess_page().
*/
function mytheme_preprocess_page(&$variables) {
$variables['year'] = date('Y', time());
}
Now, in your page.html.twig you can use:
{{ year }}
// Prints '2020'