Not able to view thumbnail image for pptx,xslx extension files

Hi ,
As per the below article we are able to get the thumbnail for the attachment(eg: Image/jpg format) which we have uploaded during ticket creation.

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but we are unable to get the thumbnail for pptx, xslx files.

I can see the REST API for the images as per the below

but the same thing is not available for pptx, xslx files

Do we have any other alternate REST API to get the thumbnail for the above extension file.

please advise on the above issue