Create an encrypted file system:

zfs create -o encryption=on -o keyformat=passphrase -o keylocation=prompt tank/test-enc

Check encryption:

$ zfs get encryption tank/test-enc
NAME           PROPERTY    VALUE        SOURCE
tank/test-enc  encryption  aes-256-gcm  -

Check status:

zfs get -p encryption,keystatus,keyformat,keylocation,encryptionroot