It doesn't seem likely that a PowerPoint presentation (.pptx) can be converted to Excel spreadsheet (.xlsx) as these two document formats serve different purpose, which means direct pptx to xlsx conversion is unlikely.
You could of course copy the tables, text or images from a .pptx file to .xlsx when you open the presentation in PowerPoint and copy and paste what you need to to Excel, but that is not file conversion in proper sense.
Updated: January 3, 2022
Unfortunately, there is no detailed software record in the database that match this conversion.
PPTX
A pptx file extension is used for the default presentation format of latest editions of PowerPoint from Microsoft Office. PowerPoint slide shows are basically set of screens which can include text, graphic, sounds or videos used for various presentation purposes.
XLSX
Files with xlsx extension are s used by Microsoft Excel for its workbooks (spreadsheets) in Office Open XML format. XLSX is the latest spreadsheet format used by Excel with adoption of XML formatting first used in Office 2000. While older xls files were binary in nature, xlsx spreadsheets are using somewhat altered XML scheme.