The node with the * is the Elasticsearch master node. It is recommended to upgrade the node last to avoid problems electing a new master node.
Backup the existing configurations so a record exists of any customizations. Run ./techsupport-bundle-grab.sh from your Support tools directory to do this, making sure to upgrade your support tools prior to running the script. Instructions are here.
Start by installing the latest Swarm Search, which is the caringo-elasticsearch-search RPM.
The error: "ES_PATH_CONF must be set to the configuration path chown: cannot access '/etc/elasticsearch/elasticsearch.keystore': No such file or directory" displays if Elasticsearch 7 RPM was inadvertently installed. Install the caringo-elasticsearch-search RPM to proceed.