Min Max Control plugin offers to set product's minimum, maximum quantity and step of each product individually.
Define a min/max, step, decimal & default quantity for products, show a dropdown and much more on WooCommerce stores.
Allow you to set a minimum or maximum purchase quantity for the WooCommerce store.
Woocommerce Product Quantity Dropdown Plugin modify your single product page, shop page, and category page on convert qty text box to the dropdown.