Hello,
We are sorry to say that there is no way to add extra items according to category. If you are looking for a customization service based on your specific needs and requirements then please send a message using our Envato Market (codecanyon) profile contact form to click here https://codecanyon.net/user/themelooks#contact (screenshot as reference https://prnt.sc/10o0iwt ) with your requirements with details to get a quote.
Best Regards,
ThemeLooks Support Team