I don’t see the Openssl commands in the resources section

You’ll find the steps to Encrypt key material with OpenSSL and the OpenSSL commands in the AWS documentation for KMS here: https://docs.aws.amazon.com/kms/latest/developerguide/importing-keys-encrypt-key-material.html

openssl rand -out PlaintextKeyMaterial.bin 32

/ change the name ‘PublicKey.bin’ to the name of your wrapping key /

openssl rsautl -encrypt

-in PlaintextKeyMaterial.bin

-oaep

-inkey PublicKey.bin

-keyform DER

-pubin

-out EncryptedKeyMaterial.bin