Hi Ludovico Iovino,
It would be better if you asked this question in theme forum so that somebody else can get help from this.
Moodle allow to use different template for different type of pages like login, dashboard, course etc. You can change layout template for course page in the theme that you are using. However as per your query I feel that you want to change course list designs like courseera, udemy etc, for this moodle you have to override course list render at your theme level.
Check the following code in your theme config file:
$THEME->layouts = array(
// Most backwards compatible layout without the blocks - this is the layout used by default.
'base' => array(
'file' => 'default.php',
'regions' => array(),
),
// Standard layout with blocks, this is recommended for most pages with general information.
'standard' => array(
'file' => 'default.php',
'regions' => array('side-pre','side-post'),
'defaultregion' => 'side-pre',
),
// Main course page.
'course' => array(
'file' => 'default.php',
'regions' => array('side-pre','side-post'),
'defaultregion' => 'side-pre',
'options' => array('langmenu' => true),
),
'coursecategory' => array(
'file' => 'default.php',
'regions' => array('side-pre','side-post'),
'defaultregion' => 'side-pre',
),
// Part of course, typical for modules - default page layout if $cm specified in require_login().
'incourse' => array(
'file' => 'default.php',
'regions' => array('side-pre','side-post'),
'defaultregion' => 'side-pre',
),
// The site home page.
'frontpage' => array(
'file' => 'default.php',
'regions' => array('side-pre', 'side-post', 'content-bottom'),
'defaultregion' => 'side-pre',
'options' => array('nonavbar' => true),
),
// Server administration scripts.
'admin' => array(
'file' => 'default.php',
'regions' => array('side-pre'),
'defaultregion' => 'side-pre',
'options' => array('fluid' => true),
),
// My dashboard page.
'mydashboard' => array(
'file' => 'default.php',
'regions' => array('side-pre','side-post'),
'defaultregion' => 'side-pre',
'options' => array('langmenu' => true),
),
// My public page.
'mypublic' => array(
'file' => 'default.php',
'regions' => array('side-pre','side-post'),
'defaultregion' => 'side-ppre',
),
'login' => array(
'file' => 'default.php',
'regions' => array(),
'options' => array('langmenu' => true, 'nonavbar' => true),
),
// Pages that appear in pop-up windows - no navigation, no blocks, no header.
'popup' => array(
'file' => 'popup.php',
'regions' => array(),
'options' => array('nofooter' => true, 'nonavbar' => true),
),
// No blocks and minimal footer - used for legacy frame layouts only!
'frametop' => array(
'file' => 'default.php',
'regions' => array(),
'options' => array('nofooter' => true, 'nocoursefooter' => true),
),
// Embeded pages, like iframe/object embeded in moodleform - it needs as much space as possible.
'embedded' => array(
'file' => 'embedded.php',
'regions' => array()
),
// Used during upgrade and install, and for the 'This site is undergoing maintenance' message.
// This must not have any blocks, links, or API calls that would lead to database or cache interaction.
// Please be extremely careful if you are modifying this layout.
'maintenance' => array(
'file' => 'maintenance.php',
'regions' => array(),
),
// Should display the content and basic headers only.
'print' => array(
'file' => 'default.php',
'regions' => array(),
'options' => array('nofooter' => true, 'nonavbar' => false),
),
// The pagelayout used when a redirection is occuring.
'redirect' => array(
'file' => 'embedded.php',
'regions' => array(),
),
// The pagelayout used for reports.
'report' => array(
'file' => 'default.php',
'regions' => array('side-pre'),
'defaultregion' => 'side-pre',
),
// The pagelayout used for safebrowser and securewindow.
'secure' => array(
'file' => 'secure.php',
'regions' => array('side-pre'),
'defaultregion' => 'side-pre'
),
);