Yes, if you want to make a fighting game, my suggestion for you is to turn off all Unreal physics, and turn off all Unreal networking, and then build both physics and networking on your own. You can use Unreal animations, and you can use Unreal collision detection, but you probably can’t use the rigid body dynamics, nor the Chaos destruction.
This is a highly specialized application, building your own physics to work with your own networking to work with the kind of gameplay you want. Of course nobody will have read your mind and built it for you, ahead of time, for $99!
That was a full studio working on the game. That’s not going to be “a plugin” that you can buy on the marketplace.
Unreal Engine has made certain decisions at the core. It works great for shooters, and also pretty good for action-adventure type titles. It can be made to work for RPGs, and car racing games, and of course almost anything can work with a turn-based system. You can’t really stretch it to “deterministic lockstep” like an RTS, or to “deterministic replay” like a fighter. Those games are too niche and just work differently than what’s at the core of the Unreal physics/networking system. You will also note that the Unreal FAQ itself says that developers with “MMO” type requirements often end up putting in their own networking as well.
Luckily, you can re-use all of the Unreal graphics and scripting and asset and gameplay systems – you just need to re-build physics and networking, and then, each frame, extract the positions/poses of all the actors on the screen from your simulation, and render them.
Good luck!