I have an NPC in my project that works with an AI Controller and Behavior Tree.
You will need to add the NPC from the free Epic Games project "LYRA" to my project.
You will need to make the AI Controller and Behavior Tree of the new NPC similar to that of the existing NPC, namely using VisAI.
Also, from LYRA, you need to take the logic of the NPC weapons.
No need to take character or weapon textures, as we have our own.
Nothing for multiplayer needs to be taken over.