Graphics and Rendering Settings
Fortnite doesn't give you a ton of graphics options. However, the most important knobs and dials are easy enough to manipulate. Beyond the universal image-quality presets (Low, Medium, High, and Epic), you can individually adjust view distance, shadow quality (the most demanding graphics parameter), anti-aliasing, and texture quality. Show Grass, a resource-hungry option on lower-end graphics cards, has its own toggle.
High vs. Epic
Differences between the High and Epic presets are not obvious. Looking closely, however, the shading and lighting are slightly dissimilar. Overall, we suspect that you'll find the High setting perfectly suitable if it means enjoying a smoother frame rate on your hardware.
Medium vs. Epic
Shadow quality takes a hit under the Medium preset, while Show Grass is disabled by default. (You can turn this setting back on independently.) There is also a noticeable decrease in texture quality, as well as in view distance.
Low vs. Epic
The Low setting is clearly designed for entry-level GPUs, as far down as integrated graphics engines. Basic image quality and the complete absence of shadows wrecks the game's visual appeal. Skip this option unless you have no other choice, in which case consider upgrading your PC.