How to set dns over tls in fedora silverblue

i use nextdns conf
/etc/systemd/resolved.conf to edit and use this as dns
but i could not find anything like this can anyone help

Should be the same process as in that thread.
man resolved.conf

DNSOverTLS=
           Takes a boolean argument or "opportunistic". If true all connections to the server will be encrypted. Note that this mode requires a DNS server that supports DNS-over-TLS and
           has a valid certificate. If the hostname was specified in DNS= by using the format "address#server_name" it is used to validate its certificate and also to enable Server Name
           Indication (SNI) when opening a TLS connection. Otherwise the certificate is checked against the server's IP. If the DNS server does not support DNS-over-TLS all DNS requests
           will fail.

           When set to "opportunistic" DNS request are attempted to send encrypted with DNS-over-TLS. If the DNS server does not support TLS, DNS-over-TLS is disabled. Note that this mode
           makes DNS-over-TLS vulnerable to "downgrade" attacks, where an attacker might be able to trigger a downgrade to non-encrypted mode by synthesizing a response that suggests
           DNS-over-TLS was not supported. If set to false, DNS lookups are send over UDP.

           Note that DNS-over-TLS requires additional data to be send for setting up an encrypted connection, and thus results in a small DNS look-up time penalty.

           Note that in "opportunistic" mode the resolver is not capable of authenticating the server, so it is vulnerable to "man-in-the-middle" attacks.

           In addition to this global DNSOverTLS= setting systemd-networkd.service(8) also maintains per-link DNSOverTLS= settings. For system DNS servers (see above), only the global
           DNSOverTLS= setting is in effect. For per-link DNS servers the per-link setting is in effect, unless it is unset in which case the global setting is used instead.

           Defaults to "no".

           Added in version 239.