TLDR adds new facial sculpts, as well as extended versions of the existing sculpts, to the LooksMenu/Plastic Surgery menu.

Customize your face shape beyond the tiny amount allowed normally, and in ways that are simply not possible before.

Existing characters/NPCs aren't changed unless you want them to be. This is purely an addition, not a replacement.

Males and females both benefit, since Bethesda made the both good and bad decision to use similar skeletons for everything.

However, due to a bug in the looks menu, having Male installed will cause the Female list to revert to vanilla. This is purely cosmetic - changes to female faces will persist as long as the female sculpt file is present, and extended female presets will load fine.