How to update the data of the "child" model?

Question

Angular

Hello everybody!
There are news with tags attached to them, that is, the News model is as follows:

import {Tags} from "./Tags";
export class News{
    id: number;
    title: string;
    text: string;
    tags: Tags;
}

Accordingly, it is this json structure that comes from the backend, that is, for each news, an array of tags comes.
Interested in how to update data when adding / removing a tag (all data comes from the backend)? If we update the news, then everything is clear, in the template new ones are simply loaded immediately after the response:
component:

this.http.get<News>('http://site.ru/api/add_news?news_id=' + news_id)
            .subscribe(
              data => { this.news = data; },
              error => { });

template:

<div *ngFor="let item of news">
  <p> {{item.title}} </p>
  <p> {{item.text}} </p>
</div>

But how do I update the tags? I'm trying to do this, but it doesn't work (and not surprisingly):
component:

this.http.get<Tags>('http://site.ru/api/add_tags?tag_name=' + tag_name)
            .subscribe(
              data => { this.tags = data; },
              error => { });

template:

<div *ngFor="let item of news">
  <p> {{item.title}} </p>
  <p> {{item.text}} </p>
  <div name="tags" *ngFor="let tag of item.tags">
  </div>
</div>

How to deal with the display of new tags, given that this is a "child" model?
Or maybe I'm not using the most optimal way?
Thanks