You can change the page dimensions after inserting them. You need to simply select the pages and go to ‘Set Page Boxes’ option under ‘More’ in the Organize Pages app.
Please let us know if this works for you.
55 votesUnder review · 20 comments · Acrobat for Windows and Mac » Page Operations · Flag idea as inappropriate… · Admin →David Kennedy commented
I often combine sets of evidence documents that range in size from a single column of a newspaper to 1/2 page and would like to make the page sizes in the new document more uniform for easier scrolling.