This is the basic technique I have used so far:
Dilate the text a little (because the text is black on white it's actually an erode, but it makes the text "fatter")
Add Gaussian noise (with various different amplitudes)
Clip the image values
Blur the images
Threshold the images
Erode the result, with various different values (...
To make a convincing simulation of a scanned page from a 1700s printed book, you'll need to study and analyze each step of the process it has went through. Since there is a variety in how scanned pages look, you'll have to determine some parameters you can randomize to create diverse samples.
I thought the whole idea with machine learning was to be able to ...
I would suggest a combination of blurring, resharpening and texture overlays.
You should find some suitable textures if you search "grunch texture" (probably then reverse them and overlay with blending mode "screen")
Here an example original text on the left text with filters on the right...
I think I found an Answer sort of https://www.youtube.com/watch?v=-OrNev6nwnA this video seems to explain A process of going about slowing the animation down. I might re-ask this if I can later because I am trying to slow the overall animation down and not just a symbol in the animation.