@Ann Calvitti‚ In-app notifications cannot be turned off and email notifications are configured at the global level, so currently, it would not be possible to adjust those based on a specific project.
I'm not entirely sure of your use case, but if you did want to "test" a few things out while the project was in a Current status, you could make a copy of the project and just remove all the assignees. Then, when you're ready, make any final updates to the original version that is still in Planning.
If you have any questions, let me know!