Hi Muhammed,
I think you can use WP’s query loop block to present those 4 posts sections.
For the dropdown list of category, I think a plugin to generate drop down list is needed.
Or you might be able to give secondary navigation a try, use this method in the blow link to re-hook it to a new location:
https://generatepress.com/forums/topic/move-secondary-navigation-after-custom-header-element/#post-952842
The new hook would be generate_before_main_content.
Let me know if you need further assistance 🙂