The important bit is -v /opt/podman/searxng/config:/etc/searxng:Z in the podman call. This will mount your local directory (i.e. on the host the container is running on) /opt/podman/searxng/config into the container as /etc/searxng (which is where SearXNG is searching for its config). Make sure that the local directory exists and is writeable by your user account before starting the container. This way your config will persist even when the container gets replaced by an updated version.

IIRC, after running the container for the first time, SearXNG should put a settings.yml and uwsgi.ini there. You can edit them and restart the container for the changes to take.

On later container updates, SearXNG will put the latest versions of the default configs as settings.yml.new and uwsgi.ini.new. This way it doesn’t overwrite your config and allows you to manually merge the new defaults into your running config. (If you only see the *.new files after starting the container for the first time, rename them and remove the .new part.)