How to specify terraform version in custom workflows when matching pre-bundled terraform versions

[kanata2]

Atlantis bundles the latest patch versions of the last 4 minor versions with the container image by default( https://github.com/runatlantis/atlantis/blob/main/Dockerfile#L119-L125 ).
I have a few questions about this.

At first, I understand that each Terraform operation will use the pre-bundled version of Terraform preferentially instead of downloading it under $HOME/atlantis/bin if that version is specified, is this correct?
In that case, I can't specify the Terraform version in a custom workflow using $HOME/atlantis/bin/terraform${ATLANTIS_TERRAFORM_VERSION}. What is the best way to specify the version of Terraform?