Help you find to the creators mentioned above.

If you meant something else (e.g., realistic injury/scar effects for character customization unrelated to self-harm), say so and I’ll provide a guide for safe, non-triggering decorative scars, wounds, or aging/texture CC for The Sims 4.

In The Sims 4 custom content community, creators develop overlays, tattoos, and skin details to represent various life experiences, including mental health journeys. These assets are typically classified under the "Skin Details" or "Tattoos" categories in CAS, allowing players to apply them across multiple outfits and ages.