An LLM can't, but StableDiffusion can. Deepfakes are very much automated for still images, and it's really just a matter of time until it's automated for video and 3D.
Even with modern tricks for Stable Diffusion to focus on a specific subject (e.g. Dreambooth LoRAs/Textual Inversion) it is not anywhere close to the level of replacing actors.
Deepfaking is still a manual process that cannot be automated, and the legal rights there are very up-in-the-air.