Create a filter in exiting WordPress Theme

Hello,

I have a premium WordPress theme installed ad I wish to add a filter to it.

Basically the filter allows you do select items and will display the volume of the selected items on the same page.

Upon confirmation, all items selected and the total volume is sent via email to the user and the website owner.

The user will have a form to fill where he put his name, email, phone number and message.

Then he receives a pdf or excel sheet with the items he selected and the total volume.

It will be a little bit like this design: https://www.lesartisansdemenageurs.fr/calculateur/calculateur-de-volume.html

This will also be responsive.

Please contact me only if you can do the job.

Thanks and regards.