How to change landscape and architecture based on player input?

I believe I would have to use a conditional node that says if customer input is this then this landscape should look like this. But is there more specific help I can get? I appreciate it. Thanks.

Let me clerify. Basically, it’s a quest-type rpg game. Let’s say a player completes a quest to fix someone’s roof. Before the quest, the roof is old and ruined. After the quest, the roof looks new.