Variants of WhatsApp CRYPT format (CRYPT8, CRYPT12 etc.) are heavily encrypted, so in order to work with the data inside you will first need to use tools that convert these files to its earliest format - CRYPT. In order to do that you will need to first convert crypt8 to crypt, which will be the first step towards achieving crypt8 to xls conversion.
After that you can use programs and websites like Whatsapp Xtract or WhatCrypt tools to export the chat backups from WhatsApp Messanger (.crypt files) and save them as in a HTML form which when viewed using a web browser will look exactly like your WhatsApp (crypt to html conversion).
Microsoft Excel and other spreadsheets nowadays accept HTML files, so you can open/import them to these programs and save in the XLS/XLSX format as spreadsheets. You can also try some of the html to xls converters.Open CRYPT8 file Open XLS file