\documentclass{article}
\usepackage[margin=1.5cm,top=1cm,headheight=16pt,headsep=0.1in,heightrounded]{geometry}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,shapes,positioning,intersections,quotes}
\begin{document}
\begin{tikzpicture}
\node[rectangle,
    draw = lightgray,
    fill = yellow,
    minimum width = .1cm, 
    minimum height = .1cm,
    font=\Huge] (rect_1)% remove at (...) and added font=\Huge
    {
    Rectangle
    };
\node[rectangle,
    draw = lightgray,
    fill = green,
    minimum width = .1cm, 
    minimum height = .1cm,
    right=2cm of rect_1,% added
    font=\Huge] (rect_2)% added font=\Huge
    {
    \begin{tabular}{cc}
		Rectangle\\
		Rectangle\\
	\end{tabular}
    };
\end{tikzpicture}
\end{document}