https://support.mozilla.org/en-US/kb/firefox-dns-over-https
By extension, any application or device could rely on DoH instead of OS-provided or network-provider DNS servers. It is controversial, since it both helps individuals combat ISP or government censorship and also helps bad actors do bad things [1].
[1]https://en.wikipedia.org/wiki/DNS_over_HTTPS#Analysis_of_DNS...
Got a source for that? No phone or browser that I'm aware of uses "hardcoded DNS resolvers". They all use the OS DNS servers which the OS gets from DHCP.