i suppose you mean you want to do that with code, and not using a tool ( because my first search would be for command line tool or automation software using a c

i suppose you mean you want to do that with code, and not using a tool ( because my first search would be for command line tool or automation software using a combination of pdf to jpg then crop then export in pdf). You could parse the pdf for that bit of text then simply recreate a new one with the correct size. But it depends a lot of how that label is printed ( using one block for the whole label or one per letter). Basically it's a lot of work or not depending on the number of cases you need to deal with. I know python has a python miner library, you may want to try that