Sorry for wasting your time you are correct secp512r1 isnt there when I run the command.
Im guessing that secp256r1 isnt in the list because its just the default one. Just using the default settings and not setting a curve uses secp256r1 and secp384r1 works by setting it in ssl_ecdh_curve.
I like CentOS its the only OS I use for servers but this kind of thing annoys me about CentOS because its waiting for Red Hat to enable secp521r1. I dont have the need for it but it would be nice to have the option.
Looking at this: https://bugzilla.redhat.com/show_bug.cgi?id=1021897#c7 it is coming but not sure when.
Thanks very much for your help.