How to add a component into a elementref?

You might be able to use Renderer2

export class AppComponent { 
@ViewChild('addButton') 
  private animateThis: ElementRef;  
  constructor(private renderer: Renderer2) {}

  addBtn() {
    const button = this.renderer.createElement('button'); 
    const buttonText = this.renderer.createText('This is a button');
    this.renderer.appendChild(button, buttonText);
    this.renderer.appendChild(this.animateThis.nativeElement, button);
  }
}

More examples

In one of my projects, I achieved something similar to your requirement this way. Let me know if it helps?

constructor(private componentFactoryResolver: ComponentFactoryResolver,
            private injector: Injector, 
            private appRef: ApplicationRef) {
  const componentFactory = this.componentFactoryResolver.resolveComponentFactory(DynamicComponent); // Your dynamic component will replace DynamicComponent

  const componentRef = componentFactory.create(this.injector);

  this.appRef.attachView(componentRef.hostView);  

  const domElem = (componentRef.hostView as EmbeddedViewRef<any>).rootNodes[0] as HTMLElement;

  const element: HTMLElement = document.createElement('div');
  element.appendChild(domElem); // Component needs to be added here
  document.body.appendChild(element);
}

This way you will have reference to your dynamic component as componentRef