Category Header pic

Hi All, just wanted to know if there is a possibility to change the individual header picture of individual category-sites without changing the header.php (Maybe somewhere in the customizer?) I don't want every category to have the same header picture as I have menu Items that are only categories. Alternatively it would also help to know if you can create a site and have all blog posts of a certain category shown under it, that would be perfect as well. Page is www.world-unlimited.de Thanks a bunch. Jessica