Easygoing Territory Defense by the Optimistic Lord: Production Magic Turns a Nameless Village into the Strongest Fortified City (2021)

Blurb:
Van, the fourth son of a powerful noble, is only two years old when he remembers his past life as a salaryman in Japan. With his adult brain in a young body, he’s considered a child prodigy …until he displays the “Production Magic” skill when he turns eight. In a family that favors offensive magic, this crafting skill is considered useless in battle, and Van is banished to oversee a tiny country town in disgrace. With only his personal maid, the memories of his past life, and his “worthless” magic, can Van improve the fortunes of this little village – and himself?

Source: www.anisearch.com/manga/79232