Drupal 8.x

I have a Drupal 8 site with the Flag module.

I want when a user creates or updates a node, product, store, group, ... the updated entity is flagged.

How to flag an entity when it is created or updated ?

I'm testing the "Rules" module which is finally (usable) in production.

But how do you flag down a new entity when it is created ?

What should be put in "Action", because it is no longer like in Drual 7 with an interface.

https://i.stack.imgur.com/jFPLB.png

I created a content type with the name 'Brand' and a field that contains three categories which are separate pages on the website. Each of those categories are also shown in the menu. Now I want to create a submenu below each category in the menu where the 'Brand' pages are shown which are connected to the selected category. Is there a way to do this in Twig?

Currently I have the following template where I want to show the items.

I've been trying to display netId through the display on the view.

So, I used hook_entity_view_alter to alter the title of the field and the field_content to be the netId.

But it doesn't seem to be working.
So, my question is 

1) Is $display->id() a machine_name of the display?

2) Is there any better way to go about?

function directories_entity_view_alter(array &$build, EntityInterface $entity, EntityViewDisplayInterface $display) {

  if ($display->id() != 'team_directory') {

    return;