Selectively run jobs in a pipeline through API request

I want to set up a MLflow - Kserve based workflow in Gitlab. I have set up two repositories. The first one contains main DS logic, and for each merge request, the CI trains the algorithm and registers a new model on MLflow. Upon manual intersections on the UI, we wish to deploy specific models through Kserve for testing (transition to staging) and production (transition to production). The second repository has a CI which has jobs for model registration, model deployment and so on. But based on user’s interaction, only one of the many jobs needs to be run.

My question is how to send a API request to Gitlab to run only job A, or only job B, etc.