$variables['current_user_profile_picture_medium'] = Drupal::entityTypeManager()->getStorage('image_style')->load('medium')->buildUrl($pp);

{{ current_user_profile_picture_medium }}

echo $this->env->getExtension('DrupalCoreTemplateTwigExtension')->escapeFilter($this->env, $this->sandbox->ensureToStringAllowed($this->getAttribute(($context["user"] ?? null), "profile_picture_medium", [])), "html", null, true);