Hello, According to https://www.pulumi.com/docs/get-started/install/#installing-previous-versions, this command should work:

brew install pulumi@2.11.2

When I try, I get the following error:

Error: No available formula or cask with the name "pulumi@2.11.2"

How can I install a previous version using brew please?

Unfortunately it's not possible at this time to install previous versions using Homebrew. You can download and install them manually from https://www.pulumi.com/docs/get-started/install/versions/.