Onyx Poke5 BOOX User Manual page 16

Cover Color
Generally, this is to darken the colors
of large cover-style icons.
Webpage Text Size
This is for the embedded WebView interface. When the DPI
adjustment is invalid, you can try to adjust the font size of the
webpage
Webpage Text Color
When bleaching does not work, you can try to adjust the webpage
colors.
Embolden Webpage Text
When some fonts cannot be emboldened, you can try to embolden
the webpage text.