Modify Opencart menu to expand sub categories

I manage an OpenCart 3 website featuring a mega menu, which you can explore at https://kozailygroup.com. Currently, when accessing the site on mobile, the main categories display a convenient button for expanding and collapsing. However, this functionality is lacking for the subcategories.

I am seeking assistance in adding a collapse/expand button for the subcategories, mirroring the user-friendly feature present in the main categories.

Thank you for your help!