Can I copy files in the Documents tool to another project?

While you can copy a set of folders in the Documents tool from one project to another, any files within those folders are not included. See Can I copy one project's Documents folders to a new project?

Yes. You can now copy both files and folders as part of project templates and from settings.

The system carries over all the files and folders. It also carries over all files that are part of any subfolder.