Understanding the use case we need a logic so that our deployment changes its logical behavior and we want to create all those deployments via single deployment plan or same template. The ideal step to achieve this is "Pre-Deployment" stage, which as name suggest is doing things before creation of deployment.
Steps to design such a template are listed below.
1: Map the process which for example going to do toggling based on reading values of release parameter to template Pre-Deployment stage. For example if a process do different configuration based on application it will deploy based on release parameter value should be mapped to this stage.
2: Now with no value to release-parameter which takes application name you can create a deployment plan, as because this stage is only going to be execute when a deployment is created from this deployment plan giving you opportunity to change the value manually or via manifest file.
3: Now you can create a deployment from this deployment plan with different release parameter values either entering in ROC UI or updating same via manifest file.