You'd want to use VPP with device based assignment for that. It requires at least macOS 10.11, and accounts for Apple's Volume Purchase Program.

would that also work for "Free" apps that are available from the App store?

Yes it would. That is because even though it is free you still have to acquire licenses like you were purchasing them.

This is partly because even though an app is free today the developer may charge for it tomorrow. This had happened to us going both ways. Had purchased thousands of the iWorks app and now they are free. We had also gotten some licenses for a free app that is now charged.

Once the licenses are purchased and the device based app deployment is setup, you can configure either the app or your full JSS to install updates routinely.

Thanks everyone for your advice. I will attempt to give it a go