Limit Font Size to 10pt in Caption

Question

The styleguide of our faculty states that notes below figures must be in font-size 10pt.

I've skipped over various posts, but none of them answering the specific 10pt solution - only small or ultra-small is given.

My document looks as follows:

\documentclass[a4paper,12pt]{article}
\usepackage{fancyhdr}
\usepackage[hmargin=2.5cm, vmargin=2cm]{geometry}
\usepackage[english]{babel}
\usepackage[utf8x]{inputenc}
\usepackage{amsmath}
\usepackage[]{graphicx}
\usepackage{float}
\usepackage{eurosym}
\usepackage{amsmath} % for equations over multiple lines
\usepackage[hang,bottom]{footmisc} % Fußzeile bleibt am Boden %
\usepackage{natbib}  % havard style citation
\usepackage{grffile}
\usepackage{bbm}
\usepackage{longtable} % table over two pages
\usepackage{graphicx}
\usepackage{caption}
\usepackage{adjustbox}
\usepackage{subcaption}

\usepackage[flushleft]{threeparttable} %note below table

\usepackage{url}
\makeatletter
\g@addto@macro{\UrlBreaks}{\UrlOrds}
\makeatother


\newtheorem{theorem}{Definition}[section]




\setlength{\parindent}{0pt}
\setlength{\footnotemargin}{0.8em}

\usepackage[titletoc,title]{appendix}
\usepackage[nottoc,notlot,notlof]{tocbibind}

\usepackage{setspace}
\setstretch{1.25} % don't modify the low-level parameter \linespread directly
\usepackage{hyperref}

\floatstyle{plaintop}
\restylefloat{table}


\begin{document}

\begin{figure}[H]
\centering
\caption{Title:This should be in normal 12pt text size}
  \includegraphics[width=\linewidth]{example-image-a}
\caption*{Note: This comment should be in  10pt text size}
\end{figure}



\begin{table}[H]
\centering
\caption{This should be in normal 12pt text size}
 \begin{threeparttable}
\begin{tabular}{lrr}
\hline\hline
\multicolumn{1}{c}{XXX}&\multicolumn{1}{c}{XXX}&\multicolumn{1}{c}{XXX (in \%)}\tabularnewline
\hline
A&$1$&$100$\tabularnewline
\text{\quad B}&$  4$&$4.37$\tabularnewline
\text{\quad \quad C}&$   24$&$0.37$\tabularnewline
\hline
\end{tabular}
\begin{tablenotes}
 \item[]Note: This comment should be in  10pt text size

\end{tablenotes}
\end{threeparttable}
\end{table}

\end{document}

Answer 1

Since you're using the article document class with a main document font size of 12pt, issuing the directive \footnotesize will produce text at a 10pt size. And, since you're also loading the caption package, you should write

...
\begin{table} % or: \begin{figure}
\captionsetup{font=footnotesize}
\caption{...} \label{...}
...
\end{table} & or: \end{figure}
...

to generate captions typeset at, you guessed it, 10pt. Note that since the \captionsetup directive is issued within a table (or figure) environment, the scope of this directive is limited to the table (or figure).

If you wanted to change the caption size globally to 10pt, you should issue the directive

\captionsetup{font=footnotesize}

in the preamble.

Answer 2

The following in a MWE that globally sets both, the table notes and the notes below figures to 10pt, while leaving the actual captions of figures and tables at a size of 12pt.

\documentclass[a4paper,12pt]{article}
\usepackage[]{graphicx}
\usepackage{float}
\usepackage{caption}
\usepackage[flushleft]{threeparttable} %note below table

\makeatletter 
\g@addto@macro\TPT@defaults{\footnotesize} 
\makeatother
\newcommand\fnote[1]{\captionsetup{font=footnotesize}\caption*{#1}}

\begin{document}

\begin{figure}[H]
\centering
\caption{Title:This should be in normal 12pt text size}
  \includegraphics[width=\linewidth]{example-image-a}
\fnote{ Note: This comment should be in  10pt text size}
\end{figure}


\begin{table}[H]
\centering
\caption{This should be in normal 12pt text size}
 \begin{threeparttable}
\begin{tabular}{lrr}
\hline\hline
\multicolumn{1}{c}{XXX}&\multicolumn{1}{c}{XXX}&\multicolumn{1}{c}{XXX (in \%)}\tabularnewline
\hline
A&1&100\tabularnewline
\quad B&  4&4.37\tabularnewline
\quad \quad C&   24&0.37\tabularnewline
\hline
\end{tabular}
\begin{tablenotes}
 \item[]Note: This comment should be in  10pt text size

\end{tablenotes}
\end{threeparttable}
\end{table}


\end{document}