You can see a showcase of a Christopher Nkunku face mod and how it looks in-game here:
The is typically designed to replace or enhance the generic in-game player model with a high-fidelity "starhead" scan or custom-made face model. Key Features
These files are usually compatible with offline modes like Career Mode and can sometimes be used in Pro Clubs via lookalike builds.
On PC, these are often distributed as .fifamod files that require tools like the FIFA Mod Manager to apply.
Some packs include updated player attributes to reflect his performance at Red Bull Leipzig or Chelsea, depending on the version of the mod.