The exact path would depend on whether you've installed magento using composer or web setup.
If you've used web setup, the files will be located here -
and for composer installation they will be here -
most of the variable of value will be located in (I think you can extrapolate relative paths for following for composer installation)
If you are extending Magento Blank theme instead of luma, you might wanna look here instead
After some further digging more variables can be found here -
and for composer installation,