How to perform one async action after another without embedded subscriptions

I would like to perform async actions one after another using rxjs. I know that embedding subscribe in a subscribe is not a good practice and there are some other rxjs operators (flatMap\mergeMap, do etc. using pipe).

I need to get the component queryparams, set a global variable (globalVar), and only then, continue with the next async action (this..doSomething()). This is my code using embedded subscriptions: *doSomething return an observable

this.route.paramMap.subscribe(params => 
    { 
      globalVar = + params['userId']; 
      this.<someService>.doSomething().subscribe(result => 
      {
        this.func1();
      });
    }