Doing Mewing is the best for the jaw line:
https://www.youtube.com/shorts/oyL54HbLxXI
The jawliners you have uploaded are rubbish, the ones I usually use are these ones. They last several weeks until they break:
https://www.amazon.es/dp/B08T79X47B?...duct_detail s
But the majority of people you see on social networks with very marked jaws have had 1 or 2 surgeries.
The minimum is a bichectomy, which is a minor surgery to remove the fat balls and any maxillofacial does it in 10 minutes, for less than €500.
And then mentoplasty, which can be with fat transfer or hyaluronic acid in the chin for minor mentoplasties and with a prosthesis in the most severe cases.