Inheriting Scale-Out Settings on a Per-App Scaling Azure Service Plan

I have a function app in an Azure service plan where I only ever want 1 instance to be running. Said service plan is used by many other apps.

The service plan has a defined ruleset for scaling that the other apps in it use. Instead of creating a whole new service plan for my function app, I would like to enable per-app scaling in the service plan so that I can change it on a per-function-app basis. However, my concern is that if I do that, the other apps in the service plan will not automatically inherit the ruleset.

What behavior should I expect if I switch my service plan over to use per-app scaling?