Let the user set the target of the link in a link field Link module has been added to core in Drupal 8, but it doesn't seem that all its features has been ported. 

For example, letting the user choose the target of the menu. In Drupal 7, the module would let me create a field and in its configuration set an option to let the user choose the target. In Drupal 8, I don't see that option.

Is that option present in Drupal 8?
You can use https://www.drupal.org/project/link_attributes for that. No, it is not in core.