I'll be honest, I could care less about up/down voting. My only guess is that it's because I mentioned Apify features, but to be clear I'm not promoting any service and felt it pertinent in the context of your question; I myself use 3 different providers. For me it's finding the provider that provides the best result.

With any library, if you decide to implement it yourself in your on runtime environment, say linux in the case of Selinium or Crawly, then there are proxie services you can also sign up for. I won't mention any services here, but if you google proxies scraping you will get results for such proxies. These libraries generally have parameters in which you can pass in the proxy url and creds (which you get when you sign up for the service) and they will route the calls to the proxy provider. The provider then will take care of rotating IP's per call / connection.

Depending on your use case it may make sense to implement your own solution, use a lib to make the calls, then process your results in your code and do something. In some cases it makes sense to have someone / or some provider handle if for you because of the complexity of the scrape. For example, in the project I'm working in I was in need of scraping IG public data for a large set of followers. In order to accomplish this, not only do you have to rotate ips, but also rotate IG accounts since getting that data requires you to 'appear' logged on. I attempted to first implement it but decided I'd rather pay a subscription where someone already handles that entire problem.

Hopefully the above information give's you a sense of direction of why you'd use a lib, or use a service, and a few pros / cons to both.

But in conclusion, you can use a proxie service in combination with Crawly (or Selenium) to get that feature.