Older Noctis
If you prefer a more grizzled, battle-worn face on Noctis, this mod's for you. You can also add a beard to his otherwise clean-shaven profile, and apply some extra length to his hair, though that's all optional. Additionally, there's a retextured gold Lucian jacket available.
Change Noctis's Hair, Eyes, Shirt, and Outfit Colors
For those seeking a more in-depth level on tweaking Noctis's appearance, this mod lets you adjust the color of his hair, eyes, shirt, and outfit colors to a respectable degree. Want a white-haired, red-eyed, blue-clad protagonist? Go for it. The author includes a 4K pack as well as a standard version, so you can try them both out and land on one that best suits your PC's performance.
ECO – Empire Character Overhaul
An ambitious project, this mod pack includes completely redesigned outfits for characters based on older Final Fantasy games, as well as an even mix of wholly new creations. As the author states: “My vision is not to just change the colors. I wanted to give those clothes a new design, a new feeling. Every retexture of these mod will fit a theme. This might be an actual trend in fashion or with older Final Fantasy characters in mind.”
You'll want to keep an eye on this mod, as the creator suggests it's an ongoing effort, with a lot more content planned for the future, including a wealth of 4K textures to accompany the standard 2K options.
Red Royal Arms
A simple but noticeable mod, this selection gives all 13 Royal Arms a menacingly deep red color. It's a great way to highlight your character's weapons in a different aspect, without changing too much of their original appearance.
Detailed Complexions
With the Detailed Complexions mod, Noctis, Gladiolus (AKA Gladio and Gladdy) Prompto, and Ignis receive scratch-built faces with excellent detail. In particular, you'll notice freckles, pores, wrinkles, and just about everything else that you'd see on someone's skin in the real world. Like some other mods on this list, this version is meant to work with the 4K high-res texture pack, so make sure you've got that setup ahead of time.