zackdesign

Turn your WordPress post categories into a search powerhouse! This plugin gives you a set of dropdown menus based on parent categories and their sub-categories. Users select one sub-category per parent, and the plugin filters posts matching the selected combination.
Available as:
<ul>
<li>Gutenberg Block — “Multi-Category Filter” in the block inserter (new in v4)</li>
<li>Classic Widget — “Multi-Category Selection” in Appearance > Widgets</li>
<li>Shortcode — <code>[mcsw]</code> on any page or post</li>
</ul>
Features:
<ul>
<li>AND / OR category filtering — find posts matching ALL or ANY selected categories</li>
<li>AJAX chained drilldown — selecting a parent dynamically loads its children</li>
<li>Pretty permalink URLs (<code>/categories/3,5/search_type/and/order/title/</code>)</li>
<li>Ordering by title or default</li>
<li>Configurable blank search behavior</li>
<li>Exclude specific categories</li>
<li>Lightweight — no jQuery, no external dependencies</li>
<li>Pagination support</li>
<li>Display form above results on category pages (optional)</li>
</ul>
Sample use case:
Real estate — set up parent categories like “Bedrooms”, “Bathrooms”, “Price Range” with sub-categories beneath them. Users filter listings by selecting from each dropdown.
Upgrading from v3.x:
<ul>
<li>PHP sessions have been removed entirely — the URL now carries all state, which means better compatibility with caching plugins, load balancers, and modern hosting</li>
<li>jQuery has been replaced with vanilla JavaScript</li>
<li>CSS classes have changed from <code>wpmcsw</code>/<code>wpmm</code> to BEM-style <code>mcsw-*</code> classes — update any custom CSS</li>
<li>The old <code>select-chain.js</code> in the plugin root has been replaced by <code>js/select-chain.js</code></li>
</ul>

Multiple Category Selection Widget

Filter posts by selecting multiple categories using dropdown menus. Available as a widget, block, or shortcode.

starblank

This free plugin shows next and previous product in single product view in same category.
Installation
Simply upload the .zip file into wordpress, then activate the plugin. A new submenu called Next/Previous Product will on Woocommerce Options left bar. 
This plugin requires Woocommerce in order to run. 
Has been tested with the new Storefront Woocommerce theme and is fully compatible with DIVI framework.
How to use
–Free Version allows: 
Show the previous and next product on the single product view of your store, from the same category, on the top the page.
—<a href="http://starblank.com/en/next-previous-products-for-woocommerce-premium/" rel="nofollow ugc">Premium Version allows:</a> 
-You can choose the location of the next /previos product links: 
 * Over the product 
 * At the bottom of the page 
 * Over the product description 
 * Below product description 
 * Floating in both sides of the screen
-Choose what product will be seen: 
 * Show only products from same subcategory 
 * From same category 
 * Show random products
<ul>
<li>
Show the image and/or the title of the product, all fully customizable in color and size
</li>
<li>
Allows you to use custom arrows instead of default ones
</li>
<li>
and much more!
</li>
</ul>
<a href="http://starblank.com/en/next-previous-products-for-woocommerce-premium/" rel="nofollow ugc">You can get the premium version here</a>
Have fun!

Next / Previous Product for Woocommerce FREE version

This free plugin shows next and previous product in single product view in same category. Installation Simply upload the .

Multiple Category Selection Widget vs Next / Previous Product for Woocommerce FREE version