Overleaf and Section Fonts

Question

Oveleaf say that it's possible to use a set of pre-installed fonts here. One of these is "CMU Classical Serif" I want to change the section title in my document to be "CMU Classical Serif"

I try the following, but the font does not change at all (using package titlesec, XeLaTex compiler for fontspec)

    \newfontfamily\sectionfonts{CMU Classical Serif}
    \titleformat*{\section}{ \center \large \bf}
    \titleformat*{\subsection}{\bf} 
    \titleformat*{\subsubsection}{\it} 

Is this a problem with Overleaf or have I done something wrong?

Edit: there are no errors, not even "font not found", just no changes...

Answer 1

You are using the deprecated font commands such as \bf they will always use the document default encoding and family, they do not combine in the way that latex2e font commands do

Presumably you want something like

\titleformat*{\section}{\centering\sectionfonts\large\bfseries}

Answer 2

I think I found a solution: I just need to define a fontfamily separately and then call this inside \titelformat* as @LianTze Lim was suggesting, i.e:

\newfontfamily\headingfont[]{Alexander} 
 \titleformat{\section}{\headingfont \centering \large\bfseries}{\S \thesection.}{0.5em}{}[{\titlerule[0.2pt]}]

(the last parts are irrelevant). Thanks also to @DavidCarlisle, although I admit I haven't checked this :)