How to find a game object with networking

I'm just getting started with understanding networking and I'm confused about what I need to do to find a game object active in the scene since I can't get GameObject.Find to return any game objects. I've got a simple Player GameObject that gets spawned for each user that joins, and when they join, I want to find and store reference to an Enemy GameObject that is already active on start.

I've tried GameObject.Find, finding by tag, and type, and including them in a Cmd function to run on the server. There's also the NetworkInstanceId in which I could use something like ClientScene.FindLocalObject(), but I don't know how to get the netId of it without already having a reference to the Enemy Game Object. I've also tried to have the Player spawn with a trigger collider within the collider of the Enemy to see if I can get the reference using OnTriggerEnter, but no success there.

If someone could correct and explain to me what should be done, I'd be very grateful. I'm sure it's likely something really simple that I've just not found asked or in a tutorial yet.