I found an easy level up cheat for Sniper Elite 4. I'm using the PS4 version but I guess it'll work for PC and xboxone also. This is what I do. At the end of the level it automatically saves for you. Well for me it did. I load up that automatic savegame and I take a few steps and the level ends. It says I've gained some XP. Instead of continuing I load up that exact same savegame again. Oh look, I've gained XP again. repeat. Oh look I've leveled up. Enjoy.