The suburb of Paris that this is set in, Montfermeil, is that in which the director grew up.
The initial scenes of crowds are footage of the genuine celebrations of France's win at the football world cup in 2018.
As stated by Ruis, Les Misérables was written by Victor Hugo and is partially set in (the town of) Montfermeil, where this movie is filmed, 157 years after the novel was published.
"Le Maire" (The Mayor)'s T shirt features the number 93, which designates the department/area of Seine-Saint-Denis, where Montfermeil is located.