It might be more conclusive. While the previous light novels built the world and characters, the final one will wrap things up. It could have a different tone, perhaps more solemn as it nears the end of the story.
We can expect a thrilling conclusion to the story. It might tie up loose ends, like the relationships between the main characters. Maybe there will be final battles against powerful foes, and we'll see how Kazuma and his party have grown throughout their adventures.
I'm not entirely sure, but it's very likely. TvTropes is a comprehensive database for all kinds of fictional works. Given Konosuba's popularity, especially in the anime and light novel world, it would make sense for there to be a section about its visual novel on TvTropes. You could check by searching for 'Konosuba visual novel' on the TvTropes website.