سلام
دستور زیر بدون هیچ بستهای مشکل شما رو حل میکنه:
\setlength\parindent{0mm}
این که چقدر این کار منطقی هست یا نه را به عهدهی خودتون میسپارم.
دستورات کلی شما به صورت زیر است:
\documentclass[twocolumn]{article}
\usepackage[top=3cm,right=2.85cm,bottom=2.5cm,left=2.5cm]{geometry}
%\usepackage{indentfirst}
\setlength\parindent{0mm}
\begin{document}
\section{first}
It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test.
It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test.
\section{second}
It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test.
It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test. It is a test.
\end{document}
این هم خروجی شما میشه:
موفق باشید.
