With the advent of Layout Builder as a means of creating easy, robust, well-designed pages, it understandable users will immediately look to how to use this for their site's homepage. But, as you'll quickly discover, the homepage provided out-of-the-box doesn't permit the use of Layout Builder since it's not a "regular" page; it solely relies on global blocks to build its content. The good news is that this is an easy change and only requires the person to have the Site Manager role to accomplish it.