Two thoughts come to mind:
1 – You could apply custom tracking to the style & then turn on highlighting for “Custom Tracking/Kerning” in the preferences.
2 – Is more involved, but fun
a. Make a new swatch color that you want your text to be highlighted with (maybe Pantone Yellow?) making sure it is a spot color and not process.
b. Make a new swatch color that is CMYK with all 0 (zero) values (be sure to make it a spot color too).
c. In your paragraph style, add underline options with a heavy weight to cover your text. You will probably need some negative offset as well to get it in the right position. For color, choose your highlight color (I picked Pantone Yellow, remember?) Be sure to select “Overprint Stroke”.
d. No goto the Ink Manager and alias the highlight color to the White swatch we made in step b.
e. Finally still in the Ink Manager, convert the White spot swatch to CMYK.
While you are editing the document, you will see your text highlighted. If you print or turn on Separations Preview, your highlight will disappear.
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