You have to open the file no matter what but their is a system for background opening of a file, then you apply what you want then you close/save it(dont forget to relinquish if central file).
Then you repeat these steps for all files from a given location.
Do note that you have to make sure you do not have the file open or linked into a open revit file otherwise it can sometimes cause issues.
I know Rhythm offers the ability to open a model in the background and close it. I also know you can set project information via getting the project information with an “Element Type” node and an element.setParameter node (See Link - https://wcbim.com/2016/07/07/set-project-info-with-dynamo/) . Not sure if the two will work hand in hand though, worth a try!
Happy Dynamo-ing!