To extend the answer into the unicode space, the unicode-math
package (using fontspec
in the background) allows mapping one (or more) ranges of alphabet symbols, say italic and upright, to another range, say bold sans upright, with the range
option. The 17 ranges (up
, it
, frak
, tt
, cal
, etc) can be restricted to lower/upper/Latin/Greek or numbers, as well.
For specific (grouped) symbols, the various \sym..{}
commands, like \symbf{}
for bold face, perform a similar function.

Key to the illustration: Italic (magenta); italic mapped to bold sans upright (red); both italic and upright mapped to bfsfup; upright version of \sym..{}
command; the \symbfsfup
command.
\documentclass[12pt]{standalone}
\usepackage{xcolor}
\usepackage{unicode-math}
\setmathfont{Asana Math}[Colour=blue]
%\setmathfont{Asana Math}[range={it},Colour=magenta]
\setmathfont{Asana Math}[range={it->bfsfup,up->bfsfup},Colour=red]
\setmainfont{Noto Serif}
\begin{document}
\begin{tabular}{rl}
\verb|range={it->bfsfup,up->bfsfup}| & $AB ab \Phi \Mu \Lambda \phi \mu \lambda 123$ \\
\end{tabular}
\end{document}
\boldmath
as I used in the referenced answer, or for a subterm inside a larger math expression, you can use\bm
from the package of that name.