The iPhonex fast charge is not marked, its charging mark and ordinary charging is the same, the iPhone fast charge can only be distinguished according to the charging time, fast charge then about 2 hours can be filled. Ordinary charging, it may take close to 3 hours. I don't know why Apple doesn't design a different icon to show the fast charge.
There is no hint, but you can see the charging speed, which can be charged to 50% for half an hour.