innerHTML is not working for some tags like button or custom tags [duplicate]

Answer 1

By default Angular is sanitizing potential unsafe content. You can tell Angular to trust your content

import { DomSanitizer } from '@angular/platform-browser';

export class AppComponent  {
  constructor(private sanitizer:DomSanitizer){
    this.html = sanitizer.bypassSecurityTrustHtml("
Header
Button");
  }
  html;
}

StackBlitz example

See also https://stackoverflow.com/a/41089093/217408