I think that you just need to find some outsourcing company that provides such services. Alternatively, you can contact here https://devoxsoftware.com/services/software-development-outsourcing/. A friend of mine ordered the development of a CMS for his site from them. He said that there were no problems, the prices were adequate, and everything was completed on time. Well, or you can look for other companies if this one does not suit you.