Can I use prismic in custom domain or subdomain?

Hello Luis, welcome to the Prismic community forum!

The short answer is: It is not possible

Prismic does not provide site domain customisations. You'll need to use a hosting service to get a custom domain name for your site, like Netlify.

Or if you were wondering about having a Custom domain for de CDN, I should point out that we do not recommend this. We have a more detail explanation about it in this other thread:

Also, a note about the repository name: It is possible to change the name of your repository, but is not possible to change the name of the API endpoint.