So, I actually found an exploit for this trophy. Something I want to mention though. This trophy is glitched. Something I've learned with Dice for BF1 & BF5 is after a patch, trophies are likely to glitch. So as long as you're going for this and get it before the next patch you should be fine. I say "should be" because I honestly don't trust Dice with their patches. And the trophy still can glitch.
All you need to do, is beat the final mission of each war story on Hardcore. Yep, it's that easy. It works Online or Offline. And before all patches, meaning if Dice ever patches the exploit, just don't update your game. A disc copy is the easiest way playing unupdated, but digital can work.
The way to pop your trophy if it glitches. Is to just resume your War Story on Hardcore. And that can work pretty successfully. However in the low chance it doesn't work, you will have to do a hard reset. Delete your profile/saved data of the game. Delete the game so it doesn't have the "Patch Problem" as I stated above. And go ahead and beat the final mission of each war story on Hardcore. I wish you the best, here is my video guide incase you need this spoken to you instead. -KC