I would like to assign a picture via PHP to a page. I've googled already but just found something like this:
https://developer.wordpress.org/themes/functionality/featured-images-post-thumbnails/
Does anyone have an idea how I can assign a picture to a page via PHP?
Furthermore the picture has to be integrated via URL and not be downloaded in my media library and not be applied from there.
I'd be grateful about some helpful answers.