Well, manual growth is great if you have a few accounts to manage but not recommended when you have a lot of clients. There are a lot of bots available online like jarvee that can help you manage client accounts easily with 4g mobile proxies are recommended for the best possible experience and fewer blocks, AC ETC. Are you can do a cloud-based solution for account management, it all depends on your budget, knowledge, and growth goals.
If you want to have multiple clients and multiple accounts then yeah, it’s impossible to do it manually. I recommend using Jarvee in that case, where you’ve got everything in one place and can monitor over your accounts easily.
managing a lot of clients manually is not possible you will definitely run into a lot of issues, you can hire VA’s to help you with that but managing VA’s will be even harder, so like the guys above said try Jarvee and see how it goes, you can always ask their support for help with the issues.