Yes these are default ports for respective services, and they are configurable, but you have to create the endpoints again and then update service configs, may be firewall rules too in prod.

> under certain OpenStack configurations?

This mostly depends on your installer, but once deployed on any port, they won't change, so if you are going to use this in any app, you should confirm with admin, which port is being used for the respective service.

So in any existing production deployment, even for upgrade, these ports won't change by themself, unless the admin would want to redeploy everything.