How to solve the Magento 2 we can't find products matching the selection issue?

There are several reasons for the Magento 2 we can't find products matching the selection issue and here are the ways to fix it:

Way 1. Check the following things for your products:

1) Product is out of stock

2) Product status is Disabled

3) Product visibility does not include Catalog

4) Product is not assigned to that particular website.

Way 2. Navigate to your root directory via terminal and run the following commands:

php bin/magento indexer:reindex

php bin/magento cache:flush

How to get the relevant Magento Layered Navigation search results?

The Improved Layered Navigation extension for Magento 2 provides selections on category pages and on the search results page using filters. This way, your customers will get the relevant Magento Layered Navigation search results and save time searching for the right product. 

If you want to do the Magento 2 disable Layered Navigation procedure, then be careful as it can break things!