You might find my open source project SmallDocs useful. It lets Claude make presentations in Markdown which can be exported to PPT. You can define styles and make them defaults. (You can also share the native SmallDoc presentations by just sending a url.)
Homepage: https://smalldocs.org/
Example presentations:
https://smalldocs.org/s/mTBw58ut_eTAIlGkYePw6-#k=4MotlKf-sLc...
https://smalldocs.org/s/cGRzzCv7LA9Kd8BxZ4bBAP#k=B7_NNXPbpLw...