I worked for a website that had hundreds of employees. The development department probably had two dozen. Some were database devs, some were user interface devs, some were "full stack" devs, which I understand to mean they can do it all. There were people working on strictly search engine optimization. There were folks working strictly on improving the search function. That was only the dev team. The IT team was in charge of the company infrastructure like internet, servers, computers, networking, security, etc. The finance team had probably 15 people max during my time there. This company sold physical merchandise internationally from three fulfillment centers. There was a logistics team and all the fulfillment centers had dozens of employees. There was a customer service department with a couple dozen employees. There was a creative department that made content for the website. So, sound guy, film guys, editors. There was a legal department, an HR department, a product development team, a marketing team, a graphic design team, content writers, data analysts, so on.

That company was doing about $120 million per year and roughly about 300 total employees during my time there. So you can just scale those numbers up or down depending on the revenue of the company to get some idea of how personnel can grow and shrink.