How to make it possible to change site styles, logo and other parameters in Joomla 3 through the admin panel?

Question

PHP

I don't even know how to phrase the question correctly.
I saw a template for Joomla 3 a long time ago, in which the template is rebuilt through the admin panel in several steps.
From the list, you choose a color scheme, and the site is repainted.
Upload a logo and it changes throughout the site.
These are just the simplest things, in general there was rich functionality.
Do not offer through modules! Not an option.

Answer 1

This is done through template parameters . Of course, you can build a UI of any complexity, but the list of the fields themselves (what will be stored in the database and what you will get) is the only way.