‘Enable Layout Adjustment’ has been an option under Layout > Margins and Columns for a while. When enabled, it would do a very good job of adjusting page content to new settings. It’s now available when making document wide changes to page size.
File > Adjust Layout
- Simply enter the new page size [larger or smaller], turn other options on or off and hit ‘OK’ to see the results. Unfortunately there isn’t a ‘Preview’ option, but you can undo
- Margins – if you’d like to proportionally ‘Auto-adjust’ the page margins to the new page size, turn this on before you change page size or it won’t take effect
- Bleed – will adjust the size [larger or smaller] of graphic frames or shapes that are already extending to the bleed, but won’t extend objects on the edge of the page to the newly added bleed guides
- Adjust Font Size – doesn’t have to be enabled, but if it isn’t, making the page smaller or margins larger may result in overset text [note ability to set minimum/maximum sizes]