Hello kind.social, anyone has any tips on how to resize a pdf to a new page size? curent size is: 135 × 184 mm target is: 135 × 200 mm (I am using Linux: Ubuntu 22.04)

@mrsvcd LibreOffice Draw can do that.
1. Open the PDF in LibreOffice Draw
2. Click on "Page" on the top (6th option)
3. Then "Properties" (8th option)
4. On the "Page" tab, change it accordingly and hit "OK".
5. Either click the option to "Export directly as PDF" (the PDF symbol up top) or "File">"Export as"

Or just do a cheeky print to pdf from the PDF viewer of your choice but that may have some side effects..