chang size

If you don't need to edit the content directly in the re-sized copy you should consider p-lacing the original pages as links into a new file (just like placeing any other graphic).

You can use the script at https://github.com/mike-edel/ID-MultiPageImporter/releases to automate the import and scale the pages.

While InDesign has some automatic layout adjustment etc., you seem to be asking not to involve any of those features, and I'd generally agree. If you plan carefully and stay within certain guidelines, the format adjustment and liquid layout features can work very well. But for the average layout where the details were not carefully rendered, the automatic functions aren't much good except as a very rough first step.

To rescale a page from X1xY1 to X2xY2, there are four basic steps. Start with archiving the original file so that it's not lost, even as a backup for restarting this process after a crash or crisis of some kind.

• Using Document Setup, set the document to the new page size and margins.
• On the layout page, be sure all content (and layers) are unlocked. Select ALL content.
• Scale all content to the nearest general size that fits the new page. This will take some judgment, but with a little experimentation you'll find a scaling value that puts most elements at or near the size they will need to be on the new page.
• Position and scale each element on the new layout size. Adjust and update styles as you go.

For your project, I'd start by scaling all of the content to about 55-60%, which should all but fit the same content in the same space. Then tweak.

This gets more complicated if it's not a one- or few-page layout, but from your description and the size I am assuming it's not a book of many pages.