how to enlarge the whole set of upper case characters as I’d like to have a greater contrast with lower case in size. however, I’ve just finished sorting out all the kerning pairs…how can I make upper case in bigger size without going through all the spacing/kerning once again?
Transforming: Path > Transformations will transform all the glyphs in your selection, including their sidebearings. So the spacing is taken care of.
Kerning: if you change the shape of one side of a kerning pair, you will likely invalidate the kerning pair. The only way I see out of this is to keep the size change very minimal.
When you scale the upper case by a few percent, the kerning should be still OK.
And keep in mind that there are languages (like German) that use uppercase more often and having bigger caps can be annoying. I sometimes do the opposite: scale down the caps to make a more even text color.