So if I want to apply some function to a big and complex expression, I'd like to use \left( \right) because it scales the parentheses to match the expressions height. However, when doing this, extra space is introduced.
Compare f(x) and f\left(x\right):

Source:
\documentclass[12pt]{article}
\usepackage{amsmath}
\setlength{\parindent}{0em}
\begin{document}
\( f(x) \) (small) \\ \( f\left(x\right) \) (large)
\end{document}
mleftrightpackage, the extra spacing is sadly a consequence of how\left....\rightworks. (of course, one would never use\left...\rightin the example you give here, but I understand your point) – daleif Mar 03 '21 at 16:16mleftrighthas fully resolved my problem. – schuelermine Mar 03 '21 at 16:27