They adjust according to the pixel size, but you can turn that off. I keep it at 60px usually, 350dpi. I sketch at 100% Canvas size, and line at 150% for most things.
Lines:

Sketch:

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To turn off how the brush appears according to pixel size, uncheck this in Brush Settings!


Category 1
Update history
This is a reupload of something posted before! Forgot to take some materials off when I was messing around trying to make these since I ended up not using them!
Edited again to fix the images.
Edited to change price!
Added another image, edited the text.