Option one is to add the DNS config to the connection, so that NetworkManager creates your desired resolv.conf. Connections do have options, like ipv4.dns, ipv4.dns-search, ipv4.dns-options, and ipv4.dns-priority. See man nm-settings-nmcli
Option two, see “dns” in man NetworkManager.conf
In practice, something like:
# cat /etc/NetworkManager/conf.d/00-dns.conf
[main]
dns=none
I prefer option one and use option two to set dns=dnsmasq (as dnsmasq is bit smarter than the default glibc).