Use Sourcery as a code generator in your project as a Swift package's command plugin.
See: Blog post explaining how this works
To verify the plugin can be found by SwiftPM, use:
$ swift package --list
To run the code generator, you need to allow changes to the project with the --allow-writing-to-package-directory flag:
$ swift package --allow-writing-to-package-directory sourcery-code-generation
Inside a project/package that uses this command plugin, right-click the project and select "SourceryCommand" from the "SourceryPlugins" menu group.
(Requires Xcode 14)