How do I search for <Iron>X</Iron> when X could be any number?
How do I search for <Iron>10</Iron> when the number could be any number in a JSON file?
Does the “JSON file” part of this have any real significance?
Find what zone:
Search mode: Regular expression
\dmeans any digit character (0-9)
+means one or more of what precedes it
so in summary
\d+means one or more digits
For more, see this.