Fork of: https://aur.archlinux.org/packages/openvpn-update-systemd-resolved
Install on Arch Linux with makepkg -si
On any *.ovpn file, append to the end:
script-security 2
up /usr/bin/update-systemd-resolved
up-restart
down /usr/bin/update-systemd-resolved
down-pre
Verify with resolvectl that your tun0 device has the alternative DNS servers.