Free shipping is mainly for selling physical products, for example, you can set $66 as the amount to enjoy free shipping, so the vast majority of customers will try to meet the $66 threshold to enjoy the benefit.
This amount needs to be set according to your profit margin. Setting a low value is of course more attractive to customers, but it will affect your gross profit; setting it too high will lose its appeal to customers. Generally speaking, it is more appropriate to set a number between $50-100.
