Header

In Civi theme there are 2 ways to set header

Settings of this group allow you to manage the overall look and behavior of the header elements.

Header Customize will allow you to quickly change the background color; show more options or set padding to the header. Go to Admin-> Appearance -> Customize

And the second way to customize the header is that you can customize it on the page itself, here you just need: At that page -> Click Edit page on the top -> Select Page Header