How do I use hook_preprocess_page_title() on a Bootstrap subtheme?

I’ve just discovered that Drupal 8 Bootstrap theme doesn’t implement all existent hooks. So, for example, hook_theme_suggestions_page_alter() works, but hook_theme_suggestions_node_alter() doesn’t work. I’m interested on hook_preprocess_page_title(&$variables) and I wonder if it’s possible to incorporate this hook into my custom Bootstrap sub-theme. I have created the page-title.html.twig template and cleared the cache. I saw https://drupal-bootstrap.org/api/bootstrap/docs!plugins!Preprocess.md/group/plugins_preprocess/8.x-3.x but…