Install proxmox on a computer with plenty of RAM and CPU and you'll be able to create VMs which you can give out or rent out to anyone.

In regards to access, ipv4 is not a good idea. Especially not residential IP addresses., You should get ipv6 addresses maybe from a tunnelbroker. But anyways, first you need the server with the hypervisor (which is what you're looking for) and then you can slowly run tests, learn and eventually figure out networking.

Btw, it might be cheaper to simply rent a server, which would solve the issue of ip addresses. OVH has cheap servers and a proxmox install wizard.

Just please don't use it for anything sensitive until you can find someone to give a quick check up in regards to security to make sure you haven't missed anything. Unlike a regular PC, this one is expected to receive inbound connections which has its risks.

But don't worry about that too much now. Find an old computer or rent a server, install proxmox and start testing, playing around and learning.

Edit: chatgpt is good when wanting to learn this stuff. Especially gpt-4, but even gpt-3.5 will do. Just don't trust it blindly as it still messes up about 20% of the time. But it's often better than googling for tutorials since you can't often find what you're looking for.

Edit2: the setup I propose will allow you to divide a regular computer into 100s of virtual ones limited only by the total RAM, disk and CPU. If you only want a web server on dedicated hardware get a raspberry pi, because my proposal would be overkill. But it's the closest to "being your own cloud provider".