Sample script to find files that match a file name pattern and rename them?

While Dropbox doesn't offer a pre-built script like this (though maybe someone else in the forum here has something to share), Dropbox does offer an API you can use for programmatically listing and moving/renaming files, among other operations, which you could use to write a script for this. You can find everything you need to get started with the Dropbox API, including documentation, tutorials, and SDKs here. You may be interested in the Getting Started Guide and File Access Guide.

And specifically, you'd probably want to use the /2/files/list_folder[/continue] and /2/files/move_v2 endpoints. By the way, those are links to the documentation for the HTTPS endpoints themselves, but we recommend using one of the official SDKs if possible. Those have corresponding native methods for the HTTPS endpoints.