Unsubscribe multiple api subscribe in angular 14

I'm trying to unsubscribe but it's not working where I'm having one api response inside making another api call.

 this.sub = this.dataSevice.gerApp("true").pipe(switchMap(res)=> return this.dataService.getAppTwo("empty")). subscribe((res)=>console.log(res));

ngOnDestroy(){
this.sub.unsubscribe();
}