For HTTP Calls, no need to unsubscribe.

Using a list subscriptions

import { Subscription } from 'rxjs';

private subscriptions: Subscription[] = [];

this.subscriptions.push(
  // subscriptions
);

ngOnDestroy(): void {
  this.subscriptions.forEach((subscription: Subscription) => subscription.unsubscribe());
}

Using takeUntil, takeWhile

👉 takeUntil - Learn RxJS 👉 takeWhile - Learn RxJS

import { debounceTime, distinctUntilChanged, filter, takeUntil } from 'rxjs/operators';

private destroy$ = new Subject();

ngOnDestroy(){
  this.destroy$.next();
  this.destroy$.complete();
}

// someInput: FormControl = new FormControl('');
this.someInput.valueChanges
  .pipe(
		debounceTime(1000),
    distinctUntilChanged(),
    takeUntil(this.destroy$)
	).subscribe(val => {...});