Make bold year and author in in-text citation with biblatex

Question

I'm trying to get the year and the author in bold for all in-text citations.

Thanks to @moewe I already managed to get my prefered style of the Bibliography and also to print the author in the in-text citation in bold. Now there is missing the last step to get my prefered format style.

I would be very happy if someone had a hint for me. I think it's only one line that is missing but I don't know how to edit the year.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage{csquotes}
\usepackage[backend=biber,
  citestyle=ext-authoryear,
  bibstyle=ext-authortitle,
  sorting=nyt,
  introcite=label, 
  maintitleaftertitle=true,
  maxcitenames=2,
  dashed=false
]{biblatex}

\setlength{\introcitewidth}{4cm} 
\setlength{\introcitesep}{\bibhang}

\DeclareFieldFormat{bbx@introcite}{\mkbibbold{#1}}
\DeclareNameAlias{sortname}{family-given}
\renewcommand*{\mkbibnamefamily}{\textbf}

% make square brackets around citation in text
\makeatletter
\newrobustcmd*{\parentexttrack}[1]{%
  \begingroup
  \blx@blxinit
  \blx@setsfcodes
  \blx@bibopenparen#1\blx@bibcloseparen
  \endgroup}
\AtEveryCite{%
  \let\parentext=\parentexttrack%
  \let\bibopenparen=\bibopenbracket%
  \let\bibcloseparen=\bibclosebracket}
\makeatother

\AtBeginBibliography{ 
  \renewcommand*{\mkbibnamefamily}[1]{\textsc{#1}}}
  
\begin{filecontents}{Bibliography.bib}
@book{Loftin80,
    title={Subsonic Aircraft: Evolution and the Matching of Size to Performance},
    author={Laurence K. Loftin},
    year={1980},
}
\end{filecontents}
\addbibresource{Bibliography.bib}

\begin{document}
The author and year should be in bold. \autocite{Loftin80}
\printbibliography
\end{document}

Answer 1

Unfortunately, there are no built-in formats to change the citation label in this way, so we have to redefine the cite bibmacro. The definition used by ext-authoryear.cbx is inherited from authoryear.cbx (ll. 10-18 in v3.16). We just add a \printtext[bold]{...} in the right place.

That code will automatically make the citation in the bibliography bold as well, so we can drop the \DeclareFieldFormat{bbx@introcite}{\mkbibbold{#1}}.

Note that with biblatex-ext it is much easier to get square brackets around citations than with the standard styles. You don't need \parentexttrack and friends. See my answer to Biblatex, author-year, square brackets, where you find \parentexttrack in the accepted answer.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage{csquotes}
\usepackage[backend=biber,
  citestyle=ext-authoryear,
  bibstyle=ext-authortitle,
  sorting=nyt,
  introcite=label, 
  maintitleaftertitle=true,
  maxcitenames=2,
  dashed=false
]{biblatex}

\setlength{\introcitewidth}{4cm} 
\setlength{\introcitesep}{\bibhang}

\DeclareNameAlias{sortname}{family-given}

\DeclareOuterCiteDelims{parencite}{\bibopenbracket}{\bibclosebracket}

\renewbibmacro*{cite}{%
  \printtext[bold]{%
    \iffieldundef{shorthand}
      {\ifthenelse{\ifnameundef{labelname}\OR\iffieldundef{labelyear}}
         {\usebibmacro{cite:label}%
          \setunit{\printdelim{nonameyeardelim}}}
         {\printnames{labelname}%
          \setunit{\printdelim{nameyeardelim}}}%
       \usebibmacro{cite:labeldate+extradate}}
      {\usebibmacro{cite:shorthand}}}}

\AtBeginBibliography{%
  \renewcommand*{\mkbibnamefamily}{\textsc}}
  
\begin{filecontents}{\jobname.bib}
@book{Loftin80,
  title  = {Subsonic Aircraft: Evolution and the Matching of Size to Performance},
  author = {Laurence K. Loftin},
  year   = {1980},
}
\end{filecontents}
\addbibresource{\jobname.bib}

\begin{document}
The author and year should be in bold. \autocite{Loftin80}
\printbibliography
\end{document}