Ionic - Can't change DOM

Ionic Framework ionic-v3
4

Here is something that says in Angular you can’t manipulate the DOM. What are you supposed to do then if you want to make style changes dynamically?

It says that one should change the scope. How do you do that? Does that mean you need duplicate objects? If so, is that not bad practice?

What is the best solution?

This discussion suggests, to use NgZone? It also talks about additional plugins.

I try the following with no success:

   this.zone.run(() => {
     imgEl.setAttribute("class", "");
   });

I have also tried ChangeDetectorRef detectChanges().

Any advise appreciated.