I did some work on this late last year: from memory you are able to use any 
pptx (within reason, as indicated by the manual) and modify styles / slide 
templates appropriately. Note that you need to modify Slide Masters, not 
the slides themselves (again, from memory...)

For **table styles**, however, there does not exist an interface within 
PowerPoint to modify these at the style level. You need to manually modify 
the XML within your template, see 
http://www.brandwares.com/bestpractices/2015/07/xml-hacking-custom-table-styles/ 
for more information. It *does* work, and table styles are used when tables 
are generated within a slide, however even Microsoft's Office XML validator 
is unable to tell you if your table styles are correct; you need to try and 
open the document in PowerPoint and see if you get any errors.

On Tuesday, April 13, 2021 at 8:13:45 AM UTC+10 predat...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote:

> I guess I'm not seeing on the documentation where it is called out how to 
> modify those styles? Some GitHub issues I saw said to unzip the PPTX and 
> then look for some XML file that called out the four styles called out in 
> the documentation. However, that didn't make sense to me. 
>
> Does anyone have any examples of how to successfully, and clearly 
> explained, do this? 
>
> On Friday, April 9, 2021 at 11:56:19 AM UTC-5 John MacFarlane wrote:
>
>>
>> Generally speaking, the only modifications that are going to work
>> in a reference.docx or pptx are the changes to the styles
>> as described in the manual. If you add images, notes, etc.,
>> you're likely to get a corrupted file.
>>
>> Phillip Dudley <predat...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> writes:
>>
>> > I wanted to try making a PowerPoint using Pandoc and Markdown, but use 
>> a 
>> > template that had some images already in the template. I saw that you 
>> can 
>> > generate a reference document by doing:
>> >
>> > - https://pandoc.org/MANUAL.html#options-affecting-specific-writers
>> >
>> > The command:
>> >
>> > pandoc -o custom-reference.pptx --print-default-data-file reference.pptx
>> >
>> > Then I added a background image to the first slide, saved the 
>> > custom-reference. I then tried to build the new PPTX using
>> >
>> > #cat Makefile
>> > .PHONY: build
>> >
>> > build:
>> > pandoc \
>> > --reference-doc custom-pptx-reference.pptx \
>> > --output slides.pptx \
>> > content.md
>> >
>> > I then get the following errors:
>> >
>> > filbot@pop-os ~/D/D/L/PPTX> make build
>> > pandoc \
>> > --reference-doc custom-pptx-refernce.pptx \
>> > --output slides.pptx \
>> > content.md
>> > Could not find shape for Powerpoint content
>> > make: *** [Makefile:4: build] Error 63
>> >
>> >
>> > Am I misinterpreting the documentation on how to use this?
>> >
>> > -- 
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>> .
>>
>

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