is it possible to click a button while whole page data downloaded as .pptx format
Do you mean; when browsing a web page you want to download it as a PowerPoint “open format” file?
I guess there is no such browser extension, ever.
You could usually use the print button to print the page as a PDF file though.
That is a more appropriate format if you don’t absolutely need to use it for a slide presentation in Ms Powerpoint. Even the older .ppt format would be more compatible with non MS office packs.