Hi!
that field with checkboxes is the simplest way to add subtasks, but you can't track them individually. You could create a table with the tasks to follow up individually, if you consider it necessary.
That was a comment to improve the database in general.
On the other hand, to do what you need in the way it is proposed, you have at least two options: apply templates (only available in paid plans) or with automation by applying filters according to the criteria you have mentioned.
What I find easiest is to create a view for each alternative or path forward. Then you create an automation with the trigger "when a record comes into view.."
Here you update the "subtasks" field, although I am not sure that the automation options allow you to add a checkbox as you have in the image.