You can always use the node “Get All Actors Of Class” and choose the parent class and it will find all parents and children in the world. Use this with extreme caution! You should never put this node into a Tick event and if you have many of that class in the world it can drop FPS drastically. Depending on how you are doing everything and why you are doing it, you could always use Perception and/or EQS. Problem with Perception is everything needs to be of type Pawn or Character to use perception and with EQS it only returns the one best choice based on conditions you set.
It sounds like you want your NPC to find the closest stone and go mine it or something? If that’s the case, EQS is the best option for this as this is exactly what it was deigned for and will run faster than most plain BP’s you design by hand.
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