Manipulate parameters

Is there a way to manipulate parameters (https://help.github.com/en/actions/automating-your-workflow-with-github-actions/workflow-syntax-for-github-actions#jobsjob_idstepswith)?
Let’s say the action needs github.ref (https://help.github.com/en/actions/automating-your-workflow-with-github-actions/contexts-and-expression-syntax-for-github-actions#github-context) , but without the ref/-prefix

Do you mean you just get the ref name, for example the github.ref is refs/heads/master , and you just need the value is master?

You can try use the syntax ${VAR_NAMRE##*/} to do this.

You can set an output parameter with this syntax, and use this out in the downstream steps in the same job.