Some publishers (at least some French ones) use the following layout at the beginning of each chapter of a book.
The first line of the first paragraph appears in large font (say \Large) with no indentation. The second line is in smaller but still large font (say \large) the third line uses the normal font size but blackface. The special layout ends with line 4 (I assume here that the paragraph has at least four lines).
I have tried to devise how this could be achieved but I have only found (nice) things about lettrines.
I do not include a MWE since I have no clue where to begin and my MWE would be useless.
I am including an example of the layout taken from a book publised in 2012.
\documentclass[12pt,a5paper,french]{book}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel,microtype}
\UseMicrotypeSet[expansion]{alltext}
\frenchbsetup{StandardLayout=true,og= «,fg= »}
\pdfpagewidth=\paperwidth
\pdfpageheight=\paperheight
\begin{document}
\chapter{Le sang des terrassiers}
{\bfseries{\Large Métro, canaux, voies ferrées, tun-}{\large nels, les
chantiers se multipliaient dans} la France de la Belle Époque, en
milieu urbain comme en pleine nature, faisant partout surgir} les
terrassier ou «taupiers». Souvent fils de ruraux sans terre, ceux-ci
entraient dans le métier vers l’âge de seize ans. La Bretagne et
l’Auvergne fournissaient les plus gros contingents mais ils étaient
nombreux aussi à venir d’Italie. Les apprentis les plus jeunes, qu’on
appelait «les mousses», n’avaient pas plus de quatorze ans.
\end{document}

magazpackage that it mentions says that "maybe" special formatting might be addressed for the first n lines (but the package is dated 2011). however, the author is still active, and it might be worth asking him. – barbara beeton Mar 26 '18 at 15:25magazworks well for the first line. I have no clue on what to do for the second or third lines. Does the "maybe" in the documentation means "not for now". – Denis Mar 27 '18 at 14:45magaz. – Denis Mar 29 '18 at 06:09