Like mentioned in the previous thread, soft tissue and hairs do matter and add projection to your chin.
This thread will discuss why it works, why it fails and why it isn't a real fix.
Cope method
Let's destroy a cope method first. Hypertrophying your facial muscles doesn't work apart from the chewing musculature. This means you can't just train your chin to grow it bigger considering the chin primarely consists of type 1 muscle fibers.
So no, these cope exercises you see on Tiktok don't work.
What is stubble frauding?
It's when a guy uses facial hair (usually short boxed beard or stubble) to create the illusion of a taller and more projected chin.
It works, up to a point.
Mechanism of action (MOA)
Your brain can't simply perceive bones, it sees the whole face including soft tissue and musculature. So your brain can see the shape of features, shadow and contrast.
That's why stubble frauding works. You are basically drawing a new jawline on your mandible with hair.
The limits of frauding bones
There are limits to frauding. Don't expect that it will add multiple cm's of projection, we are speaking of mm's at best.
Dimorphism
One might argue that it increases dimorphism and it certainly does. There is no harm in keeping some stubble around your chin.