.kpf files?

Huh? Amazon gladly accepts PDF files for print paperback books and EPUB (and MOBI) for eBooks, both of which can be created in InDesign. As far as I know, the KPF format can only be generated by Amazon’s own Kindle Create software, and it is only for eBooks and not for print books. For print books you almost certainly want to send them a PDF, for eBook either an EPUB or MOBI. You do not need a KPF file at all.

InDesign is arguably the industry standard for creating PDFs and, perhaps a bit less arguably, for creating EPUBs. Many of us use it regularly to design both print books and eBooks that are destined for Amazon as well as elsewhere. For eBooks, after creating an EPUB in InDesign, you can run it through Amazon’s Kindle Previewer app to generate a MOBI (and to see what your eBook is likely to look like on various Kindle devices). The resulting files can all be uploaded successfully to Amazon KDP (provided that you have followed Amazon’s print and eBook publishing guidelines).

If you would like a good starting point for learning to use InDesign I can think of little better than David Blatner’s and Anne-Marie Concepción’s many InDesign video courses on Lynda.com (also now known as LinkedIn Learning). I believe that a 30-day trial membership is free, and full membership is available through many public libraries (at least in the US).

Be prepared, however, for a rather steep learning curve. InDesign is a professional-level app used by, and largely intended for, professional designers. It will gladly allow you do almost anything that you would ever want to do—and then some—but do not expect it to be either easy or painless to learn. That said, the users here on this forum (and the many good folks at InDesignSecrets.com) are here to help as best we can whenever you run into difficulties.