How can I configure certain products to be displayed in the main product section?

If you want to boost the sales of certain products in your store, you can make them appear in the search results as the main product, as explained in the Search box preferences section: 

To do so, simply go to the products section of your store admin, click on product you want to highlight, add the tag tsh-main-product in the tags section and click on Save. Please note that it may take a few minutes for Shopify to make these changes effective.

You can also watch this Shopify video to learn how to add new tags to products.