Question

How would this have to be created if possible? Can it only be created in cPanel, or is it possible to make a script for users to use without logging into cPanel that allows them to make their domain?

Answer 1

That should be possible depending on your hosting / server setup:

1. Add a wildcard domain CNAME record *.yourdomain.com;
2. Use a rewrite rule to direct all traffic to anything.yourdomain.com to a php script to handle the requests;
3. Do whatever you want in your php script: Use a header redirect, present another page in an iframe, etc.