Yeah, I almost talked about anycast IPs but it just added unnecessary complexity.

OP’s question is a bit weird but it sounds like they want to connect to a VPN server and then that server uses the client’s IP instead of its own for outbound traffic, like some sort of forwarding?

For all I know OP may be asking for a bridged VPN and it really just means to forward the remote client as if it’s on the local network.

But the way it’s worded, the same IP would be used to both talk to the server and by the server itself going outbound. It’s possible on a local network with iptables hacks but why would you even want to do this?