documentclass[10pt]{scrbook}
    usepackage{lmodern}
begin{document}
    Huge
    Not bold enough

    {bfseries Too bold}
end{document}

documentclass{article}
usepackage[T1]{fontenc}
usepackage{lmodern}
begin{document}
Huge
textbf{Bold}

fonttesta=ec-lmr10 at 25pt
{testa A bit Bold}

fonttestb=ec-lmr5 at 25pt
{testb A bit Bold}

Not Bold
end{document}

documentclass[10pt]{scrbook}
%%%%%
usepackage{scalerel}
input pdf-trans
newboxqbox
defusecolor#1{csnamestringcolor@#1endcsnamespace}
newcommandoutline[1]{leavevmode%
  defmaltext{#1}%
  setboxqbox=hbox{maltext}%
  boxgs{Q q 2 Tr thicknessspace w 0 0 0 rg 0 G}{}%
  copyqbox%
}
newcommandtextsb[2][.4]{%
  defthickness{#1}%
  outline{#2}%
}
%%%%%
begin{document}
    Huge
    Not bold enough

    textsb[.2]{.2 bold}

    textsb{.4 bold}

    textsb[.6]{.6 bold}

    textsb[.8]{.8 bold}

    textsb[1]{1.0 bold}

    {bfseries Too bold}
end{document}