I have received plenty of emails inviting me to submit work to predatory journals, but their low quality and lack of peer review and general ethics is pretty obvious and they are easy to avoid. They feel more like a spammy annoyance than a real threat.
In my experience, the author typesets themselves anyway - the journal doesn’t do this. And the clerical work is done by community volunteers - the journal doesn’t do that either.
Whenever I publish a paper, I just send them a finished PDF. There's nothing more done with it than that I believe.
Also, I have never sent a PDF for publication. I always send source files. I do not know of journals that would accept a PDF (except for early peer review).