Convert PDF pages to same size

I have a PDF created from a fillable form and two photos. One of the resulting pages is about five times larger than the others (one of the photos is big, the other not). I want to make all the pages the same size, ideally with as few steps as possible and ideally in a way that is scalable, i.e., that I could use in the future for a large pdf with many different page sizes rather than having to do each mismatched page individually.

Is there a way to do this?

I've tried reading other posts and tried priting as a pdf but that option is not available to me for reasons I don't understand. Adobe help suggests you "need Acrobat installed" for this to work, but I have a paid version installed. Seriously considering abandong Acrobat, it seems far to much money for a very clunky and feature-poor program. Hoping someone can show I'm wrong about that!