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.

bhavik.kiri

navonmeshsolution

This lightweight plugin enhances the WooCommerce checkout experience by enabling quantity updates and product removal options directly on the checkout page.
<h4>Key Features</h4>
Quantity Management: Add WooCommerce standard quantity fields directly on the checkout page. 
Product Removal: One-click product deletion from checkout. 
Dual Compatibility: Supports both Classic and Block-based WooCommerce checkout. 
Seamless Integration: Uses native WooCommerce styling and functionality. 
Mobile Friendly: Responsive design that works on all devices.
Note on Compatibility: This plugin works with the default WooCommerce quantity input. If your theme replaces or customizes the quantity selector (e.g., with plus/minus buttons), the functionality may not work as expected.
<h4>Important Compatibility Note</h4>
This plugin is designed to work exclusively with the standard WooCommerce Checkout page (including the new Checkout Blocks and the Classic shortcode). It is not compatible with custom checkout pages built using third-party page builders like:
<ul>
<li>
Elementor (WooCommerce Builder)
</li>
<li>
Divi BodyCommerce
</li>
<li>
WooLentor / CoBlocks
</li>
</ul>
<h4>Perfect For</h4>
<ul>
<li>Stores wanting to reduce checkout abandonment.</li>
<li>Improving user experience by removing the “back to cart” step.</li>
<li>Modern WooCommerce stores using block-based checkout.</li>
</ul>
<h3>Upgrade to Pro</h3>
Need better compatibility with custom themes or advanced filtering options?
Upgrade to Change Quantity on Checkout Pro for:
<ul>
<li>Advanced Compatibility: Works with themes that use custom plus/minus quantity buttons.</li>
<li>Category Filters: Choose exactly which product categories show quantity selectors.</li>
<li>Premium Support: Get faster response times and direct technical assistance.</li>
<li>AJAX Updates: Faster, refresh-free experience for your customers.</li>
</ul>
<a href="https://www.navonmeshsolution.com/product/cqoc-pro/" rel="nofollow ugc">View Pro Version Features »</a>
<h3>Support</h3>
For support, feature requests, or bug reports, please visit <a href="https://wordpress.org/support/plugin/change-quantity-on-checkout-for-woocommerce/" rel="ugc">Support</a>.

Change Quantity on Checkout for WooCommerce

Works like a charm. Should be part of WooCommerce.

Does what it says on the tin!

Allow customers to change product quantities and remove products directly from both Classic and Block-based WooCommerce checkout pages.

ThemesZone WooCommerce Ajax Quantity vs Change Quantity on Checkout for WooCommerce