How to set up GitHub Actions to developer branch?

Hi all,

Basically I would like to make a “dev” branch under the “master” branch of my theme in GitHub. I would then want to push any changes to the “dev” branch to then merge all changes to the “master” branch through a ‘pull request’.

I know how to create a branch and push changes to that branch but,
Can I make a workflow so that whenever there is a pull request all changes are uploaded automatically to the blog platform? Similar to GitHub Action but to occur only for pull requests completion.