The question was about privacy. Routing your DNS traffic through a VPN puts your unencrypted traffic out of an endpoint with all sorts of other connections. That’s a privacy gain.

Further, using DNS-over-TLS or DNS-over-Https encrypts your query end-to-end.

Using both in concert prevents the DNS servers from knowing your IP and anyone along the route from knowing your query.

Kinda. You can always route your traffic over a VPN. Further, from the unbound page:

To help increase online privacy, Unbound supports DNS-over-TLS and DNS-over-HTTPS which allows clients to encrypt their communication. In addition, it supports various modern standards that limit the amount of data exchanged with authoritative servers. These standards do not only improve privacy but also help making the DNS more robust. The most important are Query Name Minimisation, the Aggressive Use of DNSSEC-Validated Cache and support for authority zones, which can be used to load a copy of the root zone.

Edit: to be clear, I run unbound but I don’t recall how much I hardened it. The config file is fairly large and I was mostly focusing on speed and efficiency since it’s running on an already busy raspberry pi.

Authoritative name servers.

Good enough write-up about it here: https://docs.pi-hole.net/guides/dns/unbound/