you can add multiple rates, so if you want to have free shipping, you can add that one, add some conditions, i.e. if you want to offer free shipping for orders of more than X amount, give it a name and save it.
Then you can add a different rate, giving it a price, following the same logic if you want to add some conditions.
Let me know if that helps!
Within the Shopify Shipping settings, you can add rates based on the order weight and price or you can provide free shipping. See the screenshots below.
In the case of weight-based, you can give a minimum weight and maximum weight based on which the rates will be added. This is similar for price-based rates as well.
For a detailed understanding, visit: https://help.shopify.com/en/manual/shipping/setting-up-and-managing-your-shipping/setting-up-shippin...