you can apply a character style to a pageReference by it's property pageNumberStyleOverride.
Or do you like to apply formatting to certain topics?
Yes, u correct! I like to apply formatting to certain topics. For Example, If the InDesign document Index entries having the formatting like Italic that terms must be appeared in Italic after the generation of Index document.
So, as in
The problem is ID cannot store formatting information in an index entry (just like it doesn't work in variables for running headers and in cross-referenced paragraphs). You will have to think of something like marking the formatting with codes in the entries, then change them after generating the index.
For example, mark italics with [i]..[/i] in the index entry "bacteria: [i]E.Coli[/i]". After generating, use a GREP find-and-replace to remove the codes and apply italics.
[Ed.] Important: Add the original entry (without your codes) in the sort-as field! Otherwise, the example above will be sorted as 'symbol' [ (or perhaps it will come under 'i').
Thank you Jongware. I try this method...