How do people make their horses stand like this?.........................…

It's called parking out. My friend used to have a rocky that would do that. I trained my mini to do that. Imade him take one step forward, praise, repeat, until he was doing that. It's not natural for a horse to stand like that on it's own, though it does not hurt the horse in any way. It's just tradition. Gaited and saddle seat horses are taught to do this.