You want to use Third Party Certificate Based Authorization for OData API in Cloud for Customer, but you don't know how to enable it.
SAP Cloud for Customer
Currently for OData there is no capability to upload third party certificates for authentication purposes.
Cloud for Customer does not support associating a public certificate with a user.
Currently the only available feature is to use Basic Authentication as outlined in the help documentation under the term "SAP Cloud for Customer OData API".
Cert third-party Authentication C4C 3rd Authorisation , KBA , LOD-CRM-APM , Application & Performance Management , Product Enhancement