I am using my touchscreen for Qubes and having larger buttons to minimize maximize close would be helpful.
I can’t find a setting to alter these icons.
Yes. Brute force one.
Copy chosen theme from /usr/share/themes to appVM where you have GIMP, enlarge image files to your liking, rename theme directory, make tar.gz archives out of theme directory, copy theme archive to Dom0, untar archive and copy resulting theme directory to /usr/share/themes and then chose new them in Window Manager app