I am currently using the following index:
\documentclass[a4paper,11pt,twoside, openleft]{book}\definecolor{DarkDarkPurple}{RGB}{63, 22, 59}\usepackage{imakeidx}\newcommand{\boldindex}[1]{\textcolor{DarkPurple}{\textbf{#1}}\index{#1}}\makeindex[intoc]\begin{document}\boldindex{Test}\\\boldindex{tEst}\\\boldindex{teSt}\\\boldindex{tesT}\printindex\end{document}How am I able to have index every word starting with an uppercase letter, while holding a lowercase in the text?