Can I change the vector in placed pdf from RGB black to 100% K black?

[Baby Yoda]

Hello everyone, I have some pdf that I will place into InDesign and there’s quite a bit of vector lines and arrows in it, some are custom and some are preset vectors line that been done in Affinity Designer software. I get suggested that is better to use 100% K black and not rich black for small text and lines so there’s no possible ghosting effect. Hence, I will use 100% k black for small texts and lines but rich black for some parts of my book that has big gradient.

I see that I can’t edit the pdf’s elements in InDesign, so what should I do? Should I make a few version of the placed pdf in Affinity Designer so one can be used for my print version and one can use for ebook(RGB black)?

[datap6156868]

There is no possible way to edit pdf elements in InDesign but you can edit the pdf elements and it's color in Illustrator then place it back in InDesign. 

[Willi Adelberger]

Open the PDF in Acrobat Pro and go to the Preflight sextion and set up a preflight which corrects things as yyou want them. Do it once and you can later use it in a batch.