OK – so a couple of things
1. You can enable Manual Excerpts for pages by adding this PHP snippet to your site:
add_post_type_support( 'page', 'excerpt' );
https://docs.generatepress.com/article/adding-php/
That will provide the Excerpt meta field on Pages. Which will be displayed in Search results.
2. You can add a Featured Image to your Pages and choose not to display them using the Disable Elements meta. This will remove it from the single page but should still display them in your search results:
https://docs.generatepress.com/article/disable-elements-overview/
For more advanced search function you would need a plugin like Relevannsi.