angular-cli/packages/angular/cli/commands/deploy-long.md

The command takes an optional project name, as specified in the projects section of the angular.json workspace configuration file. When a project name is not supplied, executes the deploy builder for the default project.

To use the ng deploy command, use ng add to add a package that implements deployment capabilities to your favorite platform. Adding the package automatically updates your workspace configuration, adding a deployment CLI builder. For example:

"projects": {
     "my-project": {
         ...
        "architect": {
            ...
            "deploy": {
                "builder": "@angular/fire:deploy",
                "options": {}
                }
            }
        }
    }