Is it possible to change the look of a WordPress website, without code ?

Yes
 What is WordPress FSE?
 Full Site Editing (or “FSE”) is a collection of interrelated features that unlocks the ability to edit your entire site using blocks. This allows you to take advantage of the familiar and flexible experience of the Block Editor in more places
 I think from WordPress version 5.9, you can change all the site including header and footer with the new editor

 Gutenberg  Jul 19, 2022
 The Gutenberg plugin provides editing, customization, and site building features to WordPress.
 This beta plugin allows you to test bleeding-edge features … wordpress.org/plugins/gutenberg/