Hi,
My thought is also same as Saurabh's comments.
I'm not sure, but I guess that you want to update parameters in RA from your CI tool. And the CI tool can call only single REST call in one action.
If my understanding is correct, I think it is not possible to update multiple Environment parameters using REST in single call.
If the CI tool can use batch/shell script or executable file instead of REST, you may be able to implement using script or program included multi REST calls.
Or, if you can accept to use Release parameter instead of Environment parameter, you can update manifest file with multiple parameters and call /load-manifest REST API. However, you need to prepare manifest file before call the API, so I don't know it can be satisfied your requirement.
/load-manifest - CA Release Automation - 6.5 - CA Technologies Documentation
Thanks
Yas