Not every web page has the same header in my kirby websites.
You may want to look at HowTo: Insert additional rows in the HEAD of a template file for details, how to switch easy for a different <head> part for a web page.
Some pages may need a special CSS file or a special JS file…
Look at Kirby dosc: Templates > Your first template, if you don’t want to use snippets. But that is not my suggestion to you.