A Secret can also be created directly through the configuration file; however, you'll have to encode the Secret manually. Just use the kind of Secret:

// encode Secret manually
# echo '9S!g0U61699r' | base64
OVMhZzBVNjE2OTlyCg==

// create a Secret via configuration file, put encoded Secret into the file
# cat 2-7-1_secret.yaml
apiVersion: v1
kind: Secret
metadata:
  name: access-token
type: Opaque
data:
  2-7-1_access-token: OVMhZzBVNjE2OTlyCg==

// create the resource
# kubectl create -f 2-7-1_secret.yaml
secret "access-token" created