Angular ::ng-deep is set for deprecation. Below is a workaround or a solution until encapsulation is final.

encapsulate.component.ts

@Component({
  selector: 'app-encapsulate',
  templateUrl: './encapsulate.component.html',
  styleUrls: ['./encapsulate.component.scss'],
  encapsulation: ViewEncapsulation.None
})
export class EncapsulateComponent implements OnInit {
  constructor(el: ElementRef) {
    const { nativeElement } = el;
    nativeElement.className = nativeElement.tagName.toLowerCase();
    // now in your scss, you can wrap everting in .app-encapsulate or whatever your compoenent's selector is.
  }
}

Src/watched issue: angular/angular#25160