themeszone

The plugin once activated will display a quantity field with increment / decrement buttons once add to cart button is pressed (e.g. the product is added to cart). 
Thus allowing customers to change the products number in the cart with out having to go to shopping cart 
page.
<a href="http://plugins.themes.zone" rel="nofollow ugc">PLUGIN DEMO</a> 
(click “Add to Cart button to see it in action”)
Feel free to ask any questions at <a href="https://themes.zone" rel="nofollow ugc">Themes Zone</a>

ThemesZone WooCommerce Ajax Quantity

ThemesZone WooCommerce Ajax Quantity Plugin shows quantity field on product listing once customer clicks "Add to Cart" button.

RLDD

Add plus and minus quantity buttons to the WooCommerce Legacy Cart (does not support blocks).
<h4>Special Features</h4>
<ul>
<li>Responsive design for mobile</li>
<li>Generic aesthetic that integrates with your storefront design</li>
<li>Zero setup and configuration, just install and activate the plugin</li>
<li>No impact to WooCommerce templates</li>
<li>Easily controlled with CSS class: .woocommerce button.qty</li>
</ul>

Quantity Buttons for WooCommerce

Add plus and minus quantity buttons to the WooCommerce Legacy Cart (does not support blocks).

ThemesZone WooCommerce Ajax Quantity vs Quantity Buttons for WooCommerce