Do run tasks require an agent?

Does the pre-plan run task trigger before an agent starts a run? Is it possible to use a run task to trigger the creation of an agent for the run itself?

I would like to use an Azure Container Instance for runs. I would like to leave the ACI in a stopped state until a run is queued. I would like to use the pre-plan run task to trigger an automated system that starts the ACI to run the remainder of the run.