I would like to make changes to the actor after it’s been placed in the editor and before begin play ever runs. Ideally, I would like to do this when a property of the actor changes. Is this possible? I have an actor in my c++ project and some public variables showing in the editor but would love to be able to give more feedback to the designer. Plugins seem like overkill for this.
You probably want to look at overriding PostEditChangeProperty on your Actor class. From there you can respond to Actor property changes.
That was it! The “source” section on the documentation page is good as well. It actually gets triggered on any property change for any and all actors which I thought was interesting. AActor::PostEditChangeProperty | Unreal Engine Documentation