GitHub Pages offers an option for users to host sites based on repositories they own in GitHub. While cPanel doesn't offer direct integration with GitHub Pages, you can point domains managed through Reclaim to your GitHub Pages site in order to use a custom URL. Reclaim has documentation on this process available here: Domain Mapping to GitHub.
That said, GitHub also has documentation available, both on GitHub Pages in general and on mapping custom domains to GitHub Pages specifically. Their documentation should always be considered the primary source on these things, so if you're following along with our docs and run into an issue, Reclaim recommends checking their documentation to see if there are updated steps listed there.