It’s very hard to say. Are you asking if any command on any AS/400 (or a successor system) can handle converting a 53MB spoolfile to a .PDF? Or are you asking about your AS/400?
How are you determining the size of your spooled file? A 53MB spooled file is fairly large and it’s large for a .PDF. The entire i 7.1 SQL Reference manual is less than 13MB. I’m sure there are people who want such .PDFs and that you want it, but it seems to me not to be appropriate.
Do you currently have any .PDF functions?