This assumes:

• You have an ArgoCD server up and running. If not, check out my article Install Red Hat OpenShift GitOps Operator using the console (Argo CD)
• You have installed the ArgoCD CLI.
• You are able to log into ArgoCD using the CLI. If not, check out my article Log into ArgoCD using the CLI on OpenShift

The argoc proj create command can be used to create a project.

argocd proj create my-project

Likewise, you can create a YAML file that will be used to create a project.

apiVersion: argoproj.io/v1alpha1
kind: AppProject
metadata:
  name: my-project
  namespace: openshift-gitops
spec:
  clusterResourceWhitelist:
  - group: '*'
    kind: '*'
  destinations:
  - namespace: '*'
    server: '*'
  sourceRepos:
  - '*'

And then the kubectl (Kubernetes) or oc (OpenShift) apply command can be used to create the project. This is nice because the YAML file let's you specfiy exactly how you want the project to be configured.

kubectl apply -f myproject.yaml