The default system template does not have the SSH service installed, so it needs to be installed manually.
CentOS series, execute the following command after connecting via NoVNC
yum -y install openssh-server && systemctl restart sshd
Debian series, execute the following command after connecting via NoVNC
cat >> /etc/ssh/sshd_config << EOF
PasswordAuthentication yes
PermitRootLogin yes
EOF
service ssh restart
Alpine Linux, execute the following command after connecting via NoVNC
apk update && apk add openssh-server && rc-update add sshd
echo "PermitRootLogin yes">>/etc/ssh/sshd_config
service sshd start