My company has recently started using Jira, predominantly as a fault management system. We are currently using the free plan but only to get a feel for the software before upgrading to either standard/premium.
To give context to the question, the scenario is as follows:
When we decide that an issue requires some form of containment there is a checkbox the kicks off an automation which creates a containment task related to the parent issue. The containment and the parent will share the same custom field which is a label field named Vehicles affected.
When this task is approved we want an automation the creates a subtask, with the documentation and summary of the containment action, for EACH label in the field above.
On top of that (due to the size of the fleet of vehicles) there is a label for full fleet which, if selected needs to create a subtask for every vehicle in that group.
I saw this process implemented at a previous company so I know it is possible, I'm just not sure where to start.
Any help would be greatly appreciated and I have included some screenshots below for context.

