“Selfhost authorative dns” returns this for example https://wiki.selfhosted.show/DNS/

And we have two guides for the most common dns implementantations. Depending on the vpn software you can push the dns ip as part of the configuration or by using DHCP.

I also found the pihole docs for unbound rather helpful https://docs.pi-hole.net/guides/dns/unbound/.

Part of working with tech is knowing what to search for und using the right keywords. If you could give an example what guide / information you are unable to find, someone could give you an example how to search for it. I personally know a few junior devs and junior devops which use llama2 / chatgpt since they dont know how to search for it or read the docs.