There's no built-in solution for it, however as an option, you can use a bash script to achieve it.

This will create ResourceQuota objects in all namespaces except for kube-system:

#!/bin/bash

for ns in $(kubectl get ns -o jsonpath="{.items[*].metadata.name}"); # get all namespaces in cluster
do
  if [ $ns != kube-system ] # check if it's not kube-system namespace
  then 
  cat <<EOF | kubectl apply -f - # body of kubectl apply -f
  apiVersion: v1
  kind: ResourceQuota
  metadata:
    name: resource-quota-$ns
    namespace: $ns
  spec:
    hard:
      requests.cpu: "2"
      requests.memory: 10Gi
      limits.cpu: "2"
      limits.memory: 10Gi
EOF
  fi
done

Useful link:

• Create objects from stdout