with-tikz.tex

\documentclass{article}
\usepackage[headheight=45pt, includehead]{geometry} % for margins on a A4paper

\usepackage{fancyhdr}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{hyperref}
\usepackage{makecell}
\usepackage{tikz}
%\usetikzlibrary{shadings}

\pagestyle{fancy}
\fancyhf{}
\newcommand{\headfont}{\fontsize{8}{9}\selectfont}

\renewcommand{\headrule}{%
  \tikz \fill [left color=green,right color=yellow] (0,0) rectangle (\headwidth,2.5pt);
}

\fancyhf{}
\fancyhead[L]{%
\mbox{\makecell[cl]{\includegraphics[height=3\normalbaselineskip]{example-image}}}
  \headfont
  \makecell[cl]{%
    Journal on Teaching LaTeX, 1:1 (2024) 5-15 \\
    ISSN XXX-XXXX \\
    DOI: \href{https://doi.org/xx.yyyyy/zzz-zzzz\_00X.00X\_00XX}{xx.yyyyy/zzz-zzzz\_001.001\_0011}
  }}
\fancyhead[R]{\headfont
  \makecell[cr]{%
    Received: XX December, XXX \\
    Revised: XX December, XXX \\
    Published: XX December, XXXX
  }}
\fancyfoot[R]{\headfont\textbf{\thepage}}

\begin{document}

This is an example of a complicated header. The header contains an image, and a couple of boxes, put together with \verb|\makecell|. The header line (\verb|\headrule|) is a shaded rectangle made with \verb|\tikz|.

\bigskip

\lipsum[1-3]

\end{document}