Modifying already existing content

I have just downloaded the Dev Kit from both Steam and Epic Games Launcher and I’m wondering if it’s even possible to modify any of the existing content in the game (without adding any new content)? I’ve been trying for a long time to look for the “.uasset” files for the arrows in the game, but I can’t simply find a file that isn’t just meshes, textures, particles and sounds.

Where and what do I look for if I just want to modify the speed and gravity of the “arrow projectile”?

You must remap the Arrows in the PrimalGameData and insert the new Arrows from you. You must search in the Projectile files speed. Than edit the speed of the arrows and that is it.

The PrimalGameData has no relevance to projectiles. You would have to make a new projectile( in your case, a child of the arrow projectile), and then map that to a copy/child of the weapon template which you want to add that projectile to.