How do proxy Suppliers getting multiple public ip's for routing between them ?

hello all
im asking from the technical point of view, say I have setup proxy server ( squid proxy server ) on ec2 instance or DO droplet
in both cases, i will get 1 public IP to forward the request.
my question is how do the big proxy providers getting IP's bank simple ones i think they called "Datacenter IPs" not Residential IPs.
can someone please explain.
Thanks

how do the big proxy providers getting IP's bank simple ones i think they called "Datacenter IPs"

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They just have more IPs. Your VPS (EC2, Droplet, etc.) only has 1 IP address, but it could have a lot more.