In case you want to start a new project with Rails 7.0.0.rc1 (or any other alpha or Rc release) here is how to do this very simple:

1. Install the new version of the gem with

gem install -v 7.0.0.rc1 rails

1. Create a new project by specifying the version like this:

rails _7.0.0.rc1_ new rails7_example

Done 👏

Now you can start coding