You can go to WP Admin -> Rost Options to customize your website!
General tab
Where you can select site logo, icon and loader
Header tab
Note: Most of these options will be ignored if you build header using Elementor ( as described on Elementor -> Header Builder section)
Blog tab
Where you can customize layout for posts list page ( blog )
Blog Single Post tab
Where you can customize layout for single post page
Portfolios Tab
Where you can customize layout for portfolio archive page
Thumbnails tab
Where you can set image size for posts to optimize loading speed. You also need using Regenerate thumbnails plugin to delete old images and regenerate new.
Fonts tab
Where you can use prefer Google font for your site.
Colors tab
WordPress Customizer
You can also change site logo and icon from Customize area -> Site Identify panel.
The Customize screen can be also accessed from WordPress admin -> Appearance menu then Customize