How can I improve the appearance and options on mobile devices?

I understand the theme is fully responsive but it looks very bad on mobile devices. I have found another website using the same parent theme as me but this website looks amazing on mobile devices! I understand this website is using the mobi | Mobile First WordPress Responsive Navigation Menu Plugin from code canyon.

Please visit this website (https://www.budgivarna.se) and if possible can you tell me how this mobile display has been achieved? I have already requested custom work from codeable but I never received a reply.

The main function I want to achieve is having the option to switch between grid and list view. I would also like to have grid display on my homepage but I want the listings in two columns or more. The only option is one listing that takes up the full screen.

Thank you for any help or information you can provide.