documentclass[a4paper,12pt]{article}
usepackage[sansmath]{libertinust1math}

%usepackage{scalerel}
%%newcommandTimes{scaleobj{2.5}{times}}

letOldtimestimes
renewcommand{times}{mathop{mathchoice
  {vcenter{hbox{LARGE$Oldtimes$}}}
  {vcenter{hbox{large$Oldtimes$}}}
  {vcenter{hbox{footnotesize$Oldtimes$}}}
  {vcenter{hbox{scriptsize$Oldtimes$}}}
}displaylimits}

begin{document}

begin{equation*}
vec{a}timesvec{b}=
  begin{pmatrix}
    1 \
    2 \
    3
  end{pmatrix}
  times
  begin{pmatrix}
    4 \
    5 \
    6
  end{pmatrix}
end{equation*}
end{document}