I think sandbags can generally be tied to the calf, the main function is to increase the load on the foot, so as to make the foot more elastic.
And it can make you run faster, but I suggest you take four if you draw. Besides your feet, you can get two on your hands, because on the one hand, it can make your wrists stronger, on the other hand, it can match your feet and make you run faster. Because running requires the cooperation of hands and feet, otherwise the hands may not keep up with the rhythm of the feet.
It will be a little uncomfortable to tie sandbags at first, but it will be fine after a long time. Especially when you take them off, you will find yourself as light as a swan.