WARP (a client) just connects you to CF’s network.
If your server is running cloudflared (an outbound-only tunnel) then you can enroll your WARP client to reach your server, while your server is never accessible on the public web. That’s the principal behind Zero Trust.
While techinically yes, WARP can be considered as a VPN, it is just a secure tunnel to an endpoint. In which case you can argue any point-to-point tunnel is a VPN.