I think what you're really referring to is "game hacking". Most game hacks are either sold or kept private to prevent BattleEye detection.
If BattleEye detects any game hacks and you're using them, then you will be absolutely banned and even possibly hardware/IP banned which would prevent you from making a new account without a VPN and/or reformatting your computer (or sometimes even having to use another computer).
What people usually do if they don't want to buy hacks is either
1. Grab an already detected open source Fortnite hack and make it undetected + working again.
2. Make their own, if they got the programming skills, reverse engineering knowledge, etc...
3. Wait for someone to release an undetected hack publicly and use it while it's still not detected.
To answer your question simply. Any game on PC can be "modded" (hacked) in one way or another. Whether it be memory editing, packet editing, botting, modifying game files, etc...
Fortnite on PC seems to use a combination of BattlEye and EAC anti-cheats, both of which are a bit more advanced than the pathetic attempts at anti-cheats on other games such as Battlefield, CoD, CS:GO, etc.
It will be difficult to find a cheat for Fortnite that isn't a scam, and probably near impossible for anything less than a few hundred a month.