I'm not a fan of RxJS for several reasons. RxJS is pretty big in and of itself for what it does, and I find the Redux patterns easier to reason with the larger your application gets.
It’s not that big, only 11kb gzipped and also tree shakable so you can use operators that you actually need
https://bundlephobia.com/result?p=rxjs@6.5.2
As for redux, there is redux-observable which is quite scalable for managing complex workflows, even netflix uses it (since they developed redux-observable)