The apple developer video indicates some builtin magic on IOS14 allows a VPN tunnel to instead used its pushed DNS - be that OpenVPN, WireGuard, or openconnect.

https://developer.apple.com/videos/play/wwdc2020/10047/

https://developer.apple.com/documentation/networkextension/dns_settings

Does the apple configuration profile generator have the ability to generate these rules?

https://apple.nextdns.io/?configuration=

If not can we have an app that will do this for VPN providers not offering custom DNS inside the VPN?