No. All of these fields are optional. When you leave them blank, the editor inherits the settings from the ads already in the ad set: main text, headline, description, destination URL, call-to-action button, Facebook Page, Instagram profile, UTM parameters and the website event tracking pixel. This works even with ads in the Advantage+ format, which store the link in a different structure. If you fill in the Site URL, it takes priority and replaces the inherited link in all the ads you create. Advantage+ automatic enhancements (image enhancements, text enhancements, etc.) are turned off by default on new ads, so your creative goes out exactly as you uploaded it. Important: inheritance only works if the ad set already has at least one ad. In completely empty ad sets, enter the URL manually if your campaign objective requires it.