Setting a projects minimum MacOS version?

[Orvillain]

I'm running into an issue with 'path' on MacOS. This is with some custom 3rd party C++ code I am using for a node. I get this error:

Error: 'path' is unavailable: introduced in macOS 10.15

So I am guessing that somewhere the minimum Mac deployment target is probably 10.13 or something, and it needs to be set to 10.15. But I cannot see where to do this?

Sorry if this is a n00b question!