Yes, you sure can! What you will have to do is create what is called a Custom Menu. Custom Menus
From the left menu of your site editor, go to your Customizer. from there, select “Menus” > “Primary”. By clicking on “Add Items”, you can choose specific pages, categories or posts from your site to add to the menu.
Once you have added items to your menu, by dragging items to the right, you can nest items underneath other items. For Example, you could first add a Category page to your menu. Under that, add a Post from that category. Once you have added the post to the menu, drag it to the right. You should see it is now indented in your menu customizer. This will make it appear underneath the category name in your site’s menu bar.
Let us know how you go. I hope this solution works. All the best!