Hi Richard, my suggestion would be to first ask your client for what kind of values they want to store. If we're talking alphanumeric you can probably use a comma separated string, so "random,word,here" and then use an API call to fetch the field and then split it by the delimiter of your choice.
Do the values come from another system automatically, are they stored by the user when uploading / editing the resource, are they informative for the user in RS or more a "backend" connection value etc, there are probably a lot of different ways to solve it, but it all depends on what kind of behaviour your client wants/expects.
(I believe it's often called an XY problem, where the client asks for X because they believe that will give them Y)