Theme customizer allows you to customize the site in real time. You can see the changes at the same time you make any change in customizer settings.
Most of the options in customizer are coming from the WordPress core, which allows you to customize site information, logo, menu, widgets, static front page etc.
We added Header settings in the customizer. In Customizer > Header > Header Settings. It will allow you to set the minimum height of the header.
We added Logo settings in the customizer. In Customizer > Header > Logo Settings. It will allow you to adjust the maximum width of the logo.