Sure, for the AI to recognize any object as a primary target or an interest (things to investigate like noise, last seen location, etc), said object should have a Stimulus Generator component. The default player character has one of these for the same reason. So if you want a new character to have a similar role as the player, just implement the following steps:
I. Add the BPC_StimulusGenerator component to it and set its CanGenerateTargetStimulus parameter to True in the details panel.
II. Now have the new character implement the BPI_StimulusGeneration interface and copy the implementation for following functions from the default player character: RequestInterestStimulusActivation, RequestInterestStimulusDeactivation, and RetrieveStimulusGenerationCapabilities.
III. Finally, make sure that the collision settings for the Capsule and Mesh components match that of the default player character.
And that’s it. Now your enemy AI should chase/target this new character.
If you want this character to generate additional stimuli like whistle/footstep noise and so on that the enemy AI can recognize, you’ll have to copy that logic from player character bp (MakeWhistleNoise function for example) as well. I’d also suggest reading up on the documentation for the Stimulus system first to get an understanding of how they work: