My setup looks like this:
VS Code (latest version - no updates available)
Prettier code formatter (6.4.0) - Installed via VS Code extensions
Prettier/plugin-php - installed globally using:
npm install --global prettier @prettier/plugin-php

My VS code setting.json file looks like this:

    {
    "editor.codeActionsOnSave": null,
    "editor.defaultFormatter": "esbenp.prettier-vscode",
    "editor.formatOnSave": true
    }

Yes when I try to format a .php file, using either format on save or smd-shift-p nothing happens, it has zero functionality. What am I doing wrong here? Is there an installation set that I missed?

Prettier is currently working as expected for .js files, it is only plug-php that I am having issues with.