Setup etcdctl using the instructions at https://github.com/etcd-io/etcd/releases/tag/v3.4.13 (changed path to /usr/local/bin):
Note: if you want to match th etcdctl binaries with the embedded k3s etcd version, please run the curl command for getting the version first and adjust ETCD_VER below accordingly:
curl -L --cacert /var/lib/rancher/k3s/server/tls/etcd/server-ca.crt --cert /var/lib/rancher/k3s/server/tls/etcd/server-client.crt --key /var/lib/rancher/k3s/server/tls/etcd/server-client.key https://127.0.0.1:2379/version