Welcome to the Pi-hole community, ToasterPC. 
Redirecting your network traffic is not at all related to Pi-hole.
It would have to be done by your router or some piece of software that deals with routing, likely involving your VPN as well as some firewall configuration.
I'd suggest to focus your research on your VPN manufacturer's/provider's documentation and forums for a solution.
However, if you are instead just looking for a way to query specific name servers for specific domain names, GEOIP + DNS multiple resolver - #4 by Bucking_Horn may point you to a solution.