Learn how to save any screenshot or image file as a PDF using Windows Photos App. The post lists all the steps in that can help you do this.

From the Files app that comes with iOS, for example, you can convert images into PDF files by long pressing on them and choosing Create PDF from the menu that comes up.

How to combine PDFs on Windows Windows doesn't have a built-in PDF merging tool but I use a free app from the Microsoft Store called PDF Merger & Splitter by AnywaySoft.