Well, there are many ways to go and many things to know. I've been building turn-key hosting services for clients for years. For a start, it's important to know what's your technical and expertise level in that sense (you don't need to be a programmer to offer such service), and maybe have 'niche' idea to offer hosting too would be better.
For example: you can have an account with any of the Big-Tech Cloud providers, AWS, ACS, GCS, DigitalOcean etc., and rent VPSs from there and resell them to clients.
If you want to cPanel shared hosting (yikes!) there are many (gazillions) cpanel hosting resellers offer out there. A simple G search to be overwhelmed and lose it.
For VPSs, you could also rent dedicated servers from BIG providers and create Virtual Machines (VPSs) through virtualisation (most flexible and profitable).
Still, there are even more advanced technology today that makes thing even more simple and easy to manage in the cloud, while extremely flexible and powerful. This is something I'm coming up with but cannot talk about for now.
Of course, you also need a website to offer your services AND Customers and Technical support desk (we now have chatbots that can really help to reduce staff cost for startups).
Hope that helps, do not hesitate if you have more questions.