Angular: props are immutable?

App.ts

// App Component
export class AppComponent  {
  title="News title"; 
  content="A description should be here!";
}

// News component
@Component({
  selector: 'news',
  template: `
  <div>
     <h1>{{title}}</h1>
     <div>{{content}}</div>
     <button (click)="mutateProps()">Mutate!</button>
  </div>
  `,
})
export class NewsComponent  {
  @Input() title: string;
  @Input() content: string;
  mutateProps() {
    this.title = "Title changed!";
  };
}