I need to convert some PDFs from various sources into a single PDF, with uniform page size.
However, it appears that the only way to do that with Acrobat is to enlarge them all to the largest, which is unacceptable.
The only solution I've found (also suggested on these forums) is to "Print to PDF" of a different size, which is also silly (and which of course does not require Acrobat at all).
I'm aware that there are free utilities that can do this, but it seems like a really basic piece of functionality.
Am I missing something? Or is my understanding of the meaning of "crop" mistaken?
Obviously, you never want to print to PDF from Acrobat since that can be an exceptionally “lossy” operation (say bye-bye to live transparency, color management, possibly searchability, etc.). The PostScript generated by Acrobat is designed primarily for efficient printing on Adobe PostScript devices, not for generation of PDF!
The cropping capability is a subset of what Acrobat can in fact do in terms of changing page sizes. Note that this whole topic encompasses a number of possibilities including simply removing extraneous white area on edges of existing pages, adding such white space, and truly scaling pages which may or may not also provide for uniformly scaling the content of the existing page to match the dimensions of the new page.
The crop tool provides only some of this functionality. Advanced functionality is available in Acrobat Pro using the Preflight Tool and more specifically, the Fixup tools, especially in Acrobat DC. Under Fixups, got to Pages and you will find a number of tools for cropping and scaling pages.