It does do all that pretty much. It's not an OOP language.
"some plaintext" "mypassword" "salt" 100 cr:genkey
After that, you'll have an AES+GCM+256 encrypted buffer. You could also have skipped all the "mypassword"... genkey by using cr:randkey ... but then you would need to store that key somewhere.
If you choose to use CTR mode, you need to supply an IV, but the default is GCM.
Oh, and the reason there are two encrypt words there, is that one starts encryption and the other ends it. You can keep adding stuff to be encrypted, so for example you could encrypt a very large data stream on the fly if you wanted.