To use more colors in Overleaf LaTeX, one can do the following: at header
\usepackage[dvipsnames]{xcolor}
Then the following named color can be accessed:
One can access colors by
\color{RoyalBlue}
Or, in a more fancy way, define the commands at header
\newcommand{\note}[1]{{\color{Rhodamine}\noindent\textbf{\{}{#1}\textbf{\}}}}
For more information, check out Overleaf’s tutorial here: Using colors in LaTeX.