documentclass{article}
usepackage[many]{tcolorbox}
usepackage{lipsum}
% --
begin{document}
begin{tcolorbox}[
    title={Title},
    center title,
    toptitle=1mm,
    bottomtitle=1mm,
    sharp corners,%
    colback=white,
    colframe=black!75,
]
lipsum[1]
tcbsubtitle[halign=center]{Text}
end{tcolorbox}
end{document}