Best 3d boilerplate assets

I'm not quite sure where to put this... and the game I have in mind (still very just "in mind") would be multiplayer... so here I am. For 2D development I use the CorgiEngine by MoreMountains (best 60$ I've spent). While the asset is designed to be somewhat full-stack, I just extend it mercilessly. The code behind it is clean and simple; A genuine pleasure to read.
I am wondering if there are any assets for 3D that have similar boilerplate features coded in an equally professional manner. Features such as ladder climbing, run-and-slide, shooting, inventory (though I can just take this from CorgiEngine/ build my own. It's just nice if it's all together), FX tie-ins, melee, and whatnot. Price isn't really a concern, though clean and accessible code is. If I can't fully modify the package out of the box, then it's probably not going to work out.

Also if someone has already asked this, feel free to direct me to that thread.

 

I think MoreMountains has 3D stuff, if the topdown kit would work that's an option. Also check out Opsive, they have a lot of kits, and Catsoft Works has the Game Creator kit with lots of modules depending on what you need. I haven't used any of these myself so I can't comment on the code quality however.

Start here, find a 3D one with good reviews:
https://assetstore.unity.com/tools/game-toolkits