Yes, but it depends. The JSS SDK and ASP.NET Core SDK, both using Headless Services, still tie back to a Sitecore back-end where content is still managed by authors. This includes personalization and layout, all served up by the Headless Services to the consuming application. This allows you to use templates for field definitions, and also create templates to define layout structures, presentation details, etc.
However, if you decide to go headless by using something like the Item Service API, that only retrieves the content. Layout information is not included in those calls.