It's 100% possible. I'm working on a Prisma project with authentication and data protection.
The article you linked to is showing a set up that's good for messing around with Prisma, but wouldn't be used in the real world.
A real-world set up would involve a client, a server, and prisma. The server, such as a Node server, would expose a GraphQL API that has authentication and data protection. The Node server would then connect to the Prisma service to manage data storage.
The have a great set of projects that cover this set up here:
https://github.com/graphql-boilerplates/node-graphql-server
Working though all the code for the "advanced" version really helped me figure this architecture out.