Most of my products are very MVP-ish, so I dont focus too much on super clean code and high quality, but there are a few patterns that I reuse quite a bit and find useful. But this is not an exhaustive list and the examples might not be as clean as one would think.
Usually I am not using any sophisticated state Library anymore, the react hooks useState and useReducer in combination with context is absolutely sufficient, at least for UI-State. Everything else is in data persistence, which is in my case either Firebase or Graphql (= Apollo).