How to change layout in center content boxes on home page?

I want to change the layout of the "Featured Items" center box on the home page. I can't find anything in Admin to do that. There's Configuration>Featured Listing, but that's for the actual featured listing page. I was hoping for something similar to that for what's on the home page. Or do I have to create a custom page? If so, what page or include file do I need to alter? I tried to "find" the page by following this: https://www.zen-cart.com/tutorials/index.php?article=36
but it was of no help.

I would imagine that there is an "include" file somewhere for this, but how do I know what it is?

suppose depends exactly what want to do ... as far as i know it is governed by common/tpl_columnar_display.php but that page also affects 'New Products' block which is also in center column

Thanks. Actually, I abandoned this. And I have learned a lot in the past two days.

Originally I wanted my home page to only list all of my products, since I only have four. So there was a suggestion to use the "featured products" to do that. But later I found that I could just set my home page to show the product listing. So that's what I did.

Configuration > Layout Settings: set "Main Page - Opens with Category" to 1. (1 is the id of my only category)
Note that "Categories - Always Show on Main Page" has to be 1 for this to work.
And in Configuration > Index Listing, I also had to turn OFF "Show xxx - below Product Listing" for xxx = New Products, Featured Products, Special Products and Upcoming Products (4 settings).

Then I tweaked with the stylesheet to get it to look the way I wanted.

Result is here (still a work in progress, as of today):
https://www.collabiril.com/shop