1. In the search box ID 1 I activated the option Show ‘More results..’ text in the bottom of the search box. (I inserted the search block in several pages, e.g. https://economiadev.com/)
2. Then I selected a page with an Elementor Pro posts widget. So when the search box shows you a lot of results at the bottom of the results you can click on View more results and it opens the “advanced search box” in the results page:
The results page: (https://economiadev.com/busqueda-avanzada)
The search box redirects and sends the phrase query but it won’t show results by default, you have to press the Search button or select a filter from the sidebar to make it work.
I am using Gutenberg, but it kind of works. I am inserting the results block as you can see in the screenshots. Please make it show the results by default . In this page I am inserting the search box ID 12.