Hi folks. I'm trying to set up a multiple-node (multiple k8s nodes) cluster on a single Linux machine with k3s. In the k3s docs (https://rancher.com/docs/k3s/latest/en/quick-start/) I failed to find related information about such setting.

No, you can't do that. Only one copy of k3s at a time can run directly on the node. You can run multiple copies of k3s in Docker though. Check out #k3d for that.

Thank you, Brad. I would take a try for k3d.