To enable the top navigation in your mobile menu, simply go to the
Customizing ▸ Navigations ▸ Navigation Mobile menu and turn on the Mobile Top Navigation. https://prnt.sc/ojwiwn
Now your “top” menu should appear below the main menu.
I think in that case your mobile menu would be too high and your menu links might be too low. It’s a better option to place them side by side. https://prnt.sc/on10qk
If you want to do this, insert the following codes into Customizing-> General-> Additional CSS: