Similar to what happens in Germany. But there are somewhat technical details to consider, which drive this tendency:
Both German and French have longer words statistically, so a translation of e.g. a 500 page English book might result in 650-700 pages after translation. Now publishers have to ponder the question wether that's still a "handy" book or if they should split it into two.
And now happens, what we see: books with 300-350 pages look a bit small, so they increase the font size, expand the whitespace and, voila: two "decent" sized books where they "accidentally" increased their revenue too, because they can sell two books.
Both German and French have longer words statistically, so a translation of e.g. a 500 page English book might result in 650-700 pages after translation. Now publishers have to ponder the question wether that's still a "handy" book or if they should split it into two.
And now happens, what we see: books with 300-350 pages look a bit small, so they increase the font size, expand the whitespace and, voila: two "decent" sized books where they "accidentally" increased their revenue too, because they can sell two books.