How to set and use variables in node property panels

I am trying to make a system that is flexible depending on the input that a Google Sheets node (node-red-contrib-google-sheets) receives. I'd like to, depending on the input received, change the targeted Sheet/Tab in my document, using the "Cells" property of said node. However, I'm unsure as to how I can set a reference for a property instead of simply typing out a definitive target.

I'd greatly appreciate any help regarding how I can use references in properties!