This isn’t literally about Manga.

France has a long history with Bande dessinée, aka graphic novels. Like Asterix, TinTin, Gaston, Lucky Luke, etc. Their version of Comicon is a massive annual conference in Angoulême: https://angouleme.org/en/comics-festival/.

There’s already a whole ecosystem around Asterix: movies, theme parks, conventions, etc. Not as much around the other characters. What Macron is likely talking about is taking outside investment to jumpstart other ecosystems, including popular Japanese manga series. This is all about increasing foreign tourism.