Increase PDF background

Modify or increase the background of a PDF.
When to use it?
If you want to change the size of the PDF by changing the background.
What part of PDF is affected by it?
The color space and content of the PDF does not change only the sizes change. The original PDF gets a white frame.
What to watch for?
White frame size limit greater than 20%. If it is greater than this, the increase must be made twice.
How to use it?
PDF background, white frame increase.
Shows original and enlarged size.
Dimensions in mm. The size of each page can be changed separately.