Answer
A single ArgoCD instance can deploy to many clusters. You register external clusters (their API server and credentials are stored as secrets), then Applications set their destination.server (or name) to the target cluster. The ArgoCD control plane runs in one cluster and pushes desired state to the registered remote clusters.
argocd cluster add my-context # registers a cluster
# Application targets it:
destination:
server: https://remote-cluster-api
namespace: appReal-world example One central ArgoCD deploys to dev, staging, and prod clusters by targeting each cluster's API in the Application destination.