EST allows the client to request the list of CSR attributes the EST server supports. The attributes can indicate what additional metadata the client can provide or the algorithms that will be used.
In OPC UA the CSR metadata required is fixed by the specification and there is no mechanism to publish extensions. Clients are free to include additional metadata in the CSR, however, the CertificateManager may ignore it.
There is no mechanism in OPC UA to publish the algorithms which need to be used for the CSR, however, the CertificateManager will reject CSRs that do not meet its requirements.