--metadata

gcloud compute instances create VM_NAME \
  --image-family=IMAGE_FAMILY \
  --image-project=IMAGE_PROJECT \
  --metadata enable-oslogin=TRUE

Related

gcloud compute project-info add-metadata
Set up OS Login
gcloud compute ssh

See also

• gcloud compute instances create, --metadata enable-oslogin=TRUE, Ops Agent, --shielded-secure-boot