validate a base field in a particular content type Since title field is considered as base field  in Drupal 8, I opted hook_entity_base_field_info_alter to add validation to it. But when I look at that hook.

hook_entity_base_field_info_alter(&amp;$fields, \Drupal\Core\Entity\EntityTypeInterface $entity_type)


It doesn't holds a $bundle argument. So I couldn't add a validation for title field of a particular node type. How can I override it to be node type specific?
Base fields are by definition not bundle specific, you can't add something for a specific bundle in that hook.

However, what you can do is save it as a base field override. See how NodeTypeForm::save saves different default values and labels for base fields as base field overrides.